What about getting lost because you try to drive somewhere you normally ride, and forget that cars can't go on your route.

Reckless Endangerment -on every commute- (Very steep downhills, yeeeeee haaaa!! )
Show Off- those downhills are in 25 MPH speed limit zones.
Rain Man- All winter
Frosty- It's just frozen water
Trooper
Pwnage-The look on their face was priceless.
Jitterbug- Mmmm coffee.
Boy Scout- And I really was a Boy Scout
Gear Head- Nobody takes the wrench to my babies but me.
Haters Gona Hate-
N+1 !!
Spinnaker*
Beating to Windward* (* on the same commute)
Who Let The Dogs Out - Pepper Spray is my friend.

I have a LOT of the achievements, but here are a few suggestions.

Spread the Love - give a bike to a friend.
If You Got The Money, Honey - sell a bike to a friend
Family Discount - sell a bike to a friend for less than it's worth
You're Out Of The Family - dump a bike on someone for MORE than it's worth
Cheapskate - Get a GREAT deal on CL
Roads? Where we're going, we don't need "roads"! - Commute solely by MUPs and trails for one month
Lucky Luna - Forgot your headlight? It's cool. there's a full moon tonight...
Fly Me To The Moon - Forgot about that pothole (night).
Lunar Landing - Landed safely after encountering that pothole at night
Packing Heat - Carry a pistol in your bag/panniers
Dirty Harry - Fit a holster on your bike
Be Vewy, Vewy Quiet... - Hunt while on a bicycle tour
Born In The Saddle - commute over 300 days in a 12 month period

Pretty good showing, I think. I'd check quite a few more, but I'm only counting things that happened while commuting, not other riding.

(Achievement: Description)
XFree Spirit: Take an alternate, unknown route on your way home
XFreeballer: Forget to pack a set of underwear, walk around the whole day with diddly squat under your slacks.
XFlyin': Go over 30 mph
XRocketman: Go over 35 mph
XShow-off: Pass a car when it's not stuck in traffic
XSprinter: Haul ass to make a stale green or yellow light
XHardened: Get hit by a car
XHahd Baastuhd: Get hit by a car, finish the ride to your destination
XRainman: Commute through a rainstorm/thunderstorm
XFrosty: Commute while it's visibly snowing
XDesert Fox: Commute when it's over 105 degrees outside
XTrooper: Commute at least 3 times a week during all 4 seasons
XLook Ma'! No hands!: Ride without holding the handlebars for 1 mile
XPwnage: pass a road bike, while on a mountain bike. +1 if you were wearing sandals, +2 if you were carrying gear and they weren't
XJitterbug: Drink some coffee before your commute
XBoy Scout: Get a flat tire, replace it on the road because you're carrying a spare
XGear-Head: Perform your own bike repairs
XHaters Gonna Hate: Zip by a bunch of cars stuck in traffic OR get home/to work in less time than a car would have taken
XGators Gonna Gate: Pass a gator.

Additions:
XOooo Shiney!!!: New bike
XN+1: Bike acquired
XTriple (k)Lutz: Have fallen on ice
XSpinnaker: Have had a 30 mph tailwind
XBeating to windward: Have had a 30 mph headwind
XLitterbug: Lost pump/water bottle/whatever somwehere on the way

I'll never achieve this. All day in bike shorts? Gross.

I think you need to add:
Commando: Forget to pack a set of underwear, walk around the whole day hangin' free under your slacks.

How about:

Magellan: Quadrupling the distance of the direct route from home to work.

Wayfinding and Riding Styles
Free Spirit: Take an alternate, unknown route on your way home
Mashin' Potatoes: Climb a serious grade on the highest gear
Look Ma'! No hands!: Ride without holding the handlebars for 1 mile
Pwnage: pass a road bike, while on a mountain bike. +1 if you were wearing sandals, +2 if you were carrying gear and they weren't
Don't Ask Me: Give motorist directions that won't work because it's your cycling route, not the road. (oops, my bad)
Fools Rush In: Pulled off something that made your angel work overtime.
Playing Frogger: Starting and stopping in the traffic lane while trying to cross a busy road.
Split "S": Right turn to go w/traffic (left in England), then U-turn to go intended direction.

Fashion and Style issues
Diaper-legs: Forget to pack a set of underwear, walk around the whole day with your bike shorts under your slacks.
Commando!: Indeed. Diaper legs my ass.
Breezy: Why's it cold down there?
Wardrobe Malfunction: Dem's the splits.
Peepshow: Give or receive (see also: Breezy)
Just Hanging Out: Riding in the buff... Why wait for June and the WNBR?
Full Moon: Those shorts/slacks refuse to stay put, motorists can kiss your (well, you know)
Turtle Head: Hairstyle and/or sunburn that resembles a Klingon forehead
Wooden Clogs: You forget to pack your work shoes, and have to spend the day in your cycling shoes.
Yeti: Ice buildup on the mustache/beard or hair
Houston, we have a problem: Snot rocket fails to launch (you take it on the shoulder)
Drowned Rat: You were planning on interviewing in those clothes before nature decided against you.

Speed and Distance
Flyin': Go over 30 mph
Magellan: Quadrupling the distance of the direct route from home to work.
Rocketman: Go over 35 mph
Reckless endangerment: Go over 40mph
Speeds in excess of R17: (50+ MPH)
Show-off: Pass a car when it's not stuck in traffic
OVER 9000!!!!: Burn over 9000 calories/week, climb over 9000 feet/week, or bike over 9000 miles/year
Sprinter: Haul ass to make a stale green or yellow light
Iron legs: Bike 200 miles in 1 week
Haters Gonna Hate: Zip by a bunch of cars stuck in traffic OR get home/to work in less time than a car would have taken

Crashes, Accidents and Injuries
Hardened: Get hit by a car
Hahd Baastuhd: Get hit by a car, finish the ride to your destination
Triple Lutz: Have fallen on ice
Ultimate Hahd Baastuhd: Get hit by a car, the car suffers more damage than you
Clippy: Unclip left/right, fall opposite.
Dem's Da Breaks: Broken bone(s) from crash.
Clotheslined: Upper body hit by stationary object (ya' know, it's dark at night)
Grate Danger!: Crash due to a storm drain grate.
That Sucks!!!: Damage or injury due to a crash caused by storm drain grate.
Railroaded: Crash due to crossing railroad tracks.
A pinion: Riding bike while "winged" (with sprained/broken arm)
Cleared the Tower: Launched off bike by pothole
Balls of Steel: Get racked 3 times in a week.
Bagged another one: Bag on handlebar, meet front wheel.
SMIDSY: The last thing you want to hear before the ambulance hauls you off to the ER.
Abandoning Ship!!!: Ejecting yourself from the bike just before the impact.

Weather Conditions
Rainman: Commute through a rainstorm/thunderstorm
Frosty: Commute while it's visibly snowing
Desert Fox: Commute when it's over 90 degrees outside
Trooper: Commute at least 3 times a week during all 4 seasons
Spinnaker: Have had a 30 mph tailwind
Beating to windward: Have had a 30 mph headwind
Oh HELL! HAIL: Riding through a hell of a hail storm
Twister Anyone?: Doing your damnedest to avoid some cyclonic action
Hmmm Donut!: That awesome bakery is upwind again

Food and Drink
Jitterbug: Drink some coffee before your commute
Froggy: Swallow a bug
Bug In The System: Swallow whatever it was that flew in there. (see also: Froggy)
Second Look: Barf up whatever it was that flew in there.

Maintenance and Repair
Boy Scout: Get a flat tire, replace it on the road because you're carrying a spare
Life Scout: Give another cyclist your spare tube (or supplied them w/a patch and/or pump)
Eagle Scout: Bombproof wheels, Kevlar lined tires, Slimed tubes. Flats? Aren't those girls shoes?
Pragmatist: Get a flat tire, call a cab.
Gear-Head: Perform your own bike repairs
Bicycle Repair Man: Repair someone else's bike on the side of the road.
Wrench: Exclusively repair your own bike.
Tinkerer: Made/invented something for your bike.
Double Whammy: Flat both tires at the same time
Saddle Jowls: You ride so much, you have to retension your sagging Brooks.
Patch... Pump... Repeat: Your newly patched tire blows out while you are re-inflating it.
Oh... Busted!: That critical part fails at exactly the critical moment (resulting in crash).
MacGyver: repaired critical component failure with non-speced parts. +1 for use of multi tool only, +2 for use of duct tape, +5 for succesful repair using items found on side of road.

Close Encounters
Close Encounters: Fur, feathers, or fins, somethings too close for comfort.
Gators Gonna Gate: Pass a gator.
Follow the White Rabbit: Chased by a big dog
Tastes Like Chicken: Got caught by the dog
Who Let the Dogs Out: Chased by multiple dogs
Skunked: Close encounters w/the black and white.
Skunked Again: What?! Wasn't once enough?
Ow! That Stings!: Stung while riding (mine was in my left ear)
D'oh! A Deer! A Female Deer!: Close encounters with a member of the Cervidae family
Something's Squirrelly Here: Close encounters with a tree rat, +3 it manages to get (undamaged) between the front and rear wheels, -1 you hit it, -5 you crash. -∞ you kill it and/or it kills you
No!!! BULL!!!: Get chased and/or gored by future happy meal
Kamekazi: Dive bombed by bird

New and Used Bikes
Oooo Shiney!!!: New bike
N+1: Bike acquired
N-1: Destroy a bike.
Customiser: Significantly alter a bike in some way.
Hoarder: Commuted using a different bike each day of a work week.

Lost and Found
Litterbug: Lost pump/water bottle/whatever somwehere on the way
Red Light Rodeo: Your rear blinky flies off of your bike. You turn around and try/tried to grab the blinky before it gets/got run over by a car.
Moneybags!: Find paper money on the side of the road.
Paul Allen: Find more than $20 in paper money on the side of the road.
Bill Gates: Score over $50 in paper money (multiple finds count).
Scrooge McDuck: Stop to pick up change.
Philanthropist: Pass up paper money rather than stop.
Finder: Find something of value (>$20)
Tracker: Find the owner of the valuable you found and return.
Good Sam: Turn in the valuable to the police/lost and found/frantic parent.
Lucky Dog!: Reward or valuable returned to you after the appropriate actions taken to track down owner fail.
One Man's Trash: Pull out some kind of treasure.

Harassment
Lose the Haters: Been chased by car, but manage to lose it.
Drive By Fruiting: I've been Limed
Drinks On Me!: Beverage thrown at you.
Egging Me On!: Egging
Yoke's On Him: Egger gets caught, PUNished.
Hammer Time: Realize you're in a scary situation
Can't Touch This: Sprint out of scary situation
Faster Than A Speeding Bullet!: Someone takes a shot, and (fortunately) misses.

I fought the Law
And the Law Won: Convicted for offense
And Beat it: Got out of the citation.
On the Lam: In the town they're searching for you every where. But we never will be found.
Speed Demon: Stopped by police for speeding. +1 for written warning +2 for ticket.

Community Service
"Is this what you're looking for?": Stop, slow, or track person of interest (to the authorities).
The Extinguisher: Report a fire
Preacher: Successfully convert a motorist to cycling.

Group riding
The Gang's all Here: Everybody but the Red Shirt
Red Shirt: The guy who doesn't make it back with the regulars.

Idiots and Idiotic Behavior
Kirk to Enterprise: Motorist swears you beamed in.
Bandits At 6 O'Clock: Your move, causes the idiot passing behind you (w/o warning) to crash.
Stop! Drop! and Roll!: Do an endo, and still end up on your feet. ("I meant to do that...")
If Looks Could Kill: You'd be convicted of multiple homicide.
MY GAWD! It coming right for us!: Encountered bike salmon
HA-Haw!: Witness stupidity meet deserved pain
D'oh!: Getting deserved pain for stupidity
Don't Fence Me In: Let yourself inside of area you're not supposed to be
Magoo: Someone who's oblivious to the chaos that they create.

Lighting
Christmas Tree: Mistaken for a moving holiday favorite.
Landing Lights: "I thought you were a low flying aircraft."
UFO: NASA called again to complain that your lights are keeping the astronauts awake.
Instant Ninja: Batteries or Bulbs, it doesn't matter, you're now in the dark.
Smoke in the Cockpit: When your light burns out, It literally burns out.

Cargo
Soul Surfer: Transporting a surfboard on your bike.
Overload: Transport goods exceeding your bicycle's weight.
Heavy Haulage: Transport goods exceeding your body weight.

High Water
In Over Your Head: Find yourself in a body of water.
Who Needs a Boat?: Ride a flooded road.

Aw... Pooh
Scooby Doo-Doo: Those meddling kids didn't clean up after their dog again, your wheel/shoe finds evidence
Aw... Meadow Muffins: Hay! Your first step in manure.
awww $h!t: swerve to miss a patch of broken glass and end up going through a giant pile of dog poo, getting some on your clothes.

You Got Skills
Shutterbug: Capable of taking photographs while riding in traffic
Red Light, Green Light: Track stand through a complete traffic light cycle
Karate Kid: Track stand with one hand while taking a photo with the other

Experience
Veteran: Done it all, seen it all

Oh, and the ones I'm looking forward to...

Travel
Foreigner: Ride across an international boundary.
Explorer: Discover every map location in single player mode (just kidding)
Lost In Translation: Wayfinding in another language! 對不起，我不明白

(added MacGyver from a suggestion found on the parallel thread I posted at BikePortland.org)

For this morning's ride, I earned:

Jitterbug
Haters Gonna Hate
Red Light, Green Light