If you read the SS/FG forum you've probably already seen this, but since it's main purpose is commuting 30+ miles a day, I figured it'd make sense to post it here and open my ridiculous frankenbike up to y'alls comments as well.

Here's how I have my single (technically multi)-speed fixed/free multi-purpose commuter set up currently. For a better riding position I swapped out the Origin8 Mary-ripoffs for On-One Midge bars (I love them on my Karate Monkey) and added a Thomson setback seatpost. This gives me multiple hand positions for longer rides, and stretches me out a little more which is more comfortable on my back and arms. I also added a pair of Cane Creek SCR-5C brake levers and a rear brake (for when I'm running one of the freewheel gears). The levers are nice and make it easier to reach my brakes while down in the drops. The drivetrain is the most interesting part of this bike (IMHO). Since I got it I've added a second chainring so I'm now running a 44T Salsa ring with a 40T Sugino (gold for the bling) ring on the inside. On my rear wheel I have a Surly dinglecog with 17T and 21T gears, and on the other side I have a White Industries Dos Eno with 17T and 19T gears. When run with the 9 speed chain this allows me 6 different gear ratios to play with, giving me 44:17, 44:21, 40:17, and 40:21 on the fixed side, and 44:17, 44:19, 40:17, and 40:19 on the freewheel side. The only problem I've had is that I have to disengage the rear brake to run the 40:17 and 44:21 gears since it moves the wheel too much, but the other gears all maintain brake pad contact with the rear rim.

I ride it to work in the high gear, then go downtown, drop to a lower ratio and tear it up in the local parks, skidding around and blowing off stress. Then it's back to the high gear for a ride home, fixed if I want to book it or free if I want to relax. People look at me funny because of the drivetrain but it's fun and means all I have to carry with me is a multitool to do off-road, on-road, fixed, free, whatever. Less bikes cluttering the house also makes for a happier spouse.