Maybe a long shot, but why not ask.

Doing a Secret Santa gift exchange at work, and I drew a coworker who likes to bike to work like me. Anything fun or cool for 10-15 bucks? New bell? Blinkie light? Gadgets? Bags? Basically, what's the coolest cheap thing you ever bought for your bike (or wanted to)? I was thinking about a globe/ball style compass that can be mounted to handlebars. Some cheap ones on eBay, but they look cheap too! Know what I mean?

planet bike superflash. $15 - 20 last time i checked i think.

A commuter can always uses an extra light or two.

My son like cool cycling socks. lots of online shops have them. I like the superflash idea also. Just got one for myself for $18, and it obsoletes all the $6-10 ones I bought at Performance. I mounted it to my helmet.

If the coworker likes riding in the rain maybe some Kool Stop Salmon brake pads (if you know what type of brakes your coworker's bike is equipped with)? Other small things like chain lube, tubes, etc. are always useful.

Can't go wrong with a planet bike superflash.

skull cap or toe covers - assuming it gets cold where you are. Maybe a coffee cup that'll fit in a bottle cage.

CO2 tire inflator.
Superflash is outside the 10-15 budget, but PB's Binkie7 would make it. I love the Blinkie7. I use two SF's to point straight back, but the 7 puts out more light to the side than the SF does, so I use a 7 as well.

If you know his\her tire size tubes are always needed. Kind of lame but it works.
Other ideas would be small blinkies or lights that attach to the spokes.

LizardSkins protectors They make them for a lot of different components. I run the chainstay protectors and the grips

Delgado wheelset.
Oh.. wait.. you said 10-15 bucks?
Uhhh.....handlebar tassles..

Ok...seriously..I'd vote for the spoke blinkies. Chances are he doesn't have them and they're great for intersection safety.

That's not a guarantee. I'd never use an inflator, since it generates unnecessary waste, not to mention the cost of making and shipping a container of air around. The only real benefit AFAIK is that it's a bit smaller and lighter, and it's easier to get to very high pressures. Since I care absolutely zero about any of those things, an inflator wouldn't be of much use to me personally.

If he rides a road bike, some nice cork handlebar tape would be good.

Maybe a pair of those 'Y' shaped allan wrenches (I'm hoping to find some in my stocking)

Airzound! I got one last year in a gift exchange and it is great!

Airzound is well worth the money but its about $25 if I remember correctly.

Id say superflash, or tubes/tools.

Don't get the headset one that one did a number on the paint of the fork. It catches dirt then turning when steering basically turns into sandpaper.

If he's a commuter, try Nite Ize spoke lights. Got a pair delivered for about $17.

Bento box

Chamois Butt'r

Aside from a Japanese lunch, what's that?

The spoke lights are a great idea! Practical and fun. Will probably do that. Thanks for the suggestions folks. Feel free to keep this thread going since it's the season and it can help others with gift ideas.

The "Spokelit" can be had here for $6.67. Shipping is a touch high though.

I like these brass bells a lot:

https://www.velo-orange.com/bellsdingding.html

Then again, I'm a complete Fred.

PB Superflash can be had for less than $15. Find it online, take the add to Performance, and walk out with one for less than 15. No shipping, either.

A helmet cover is pretty good -- most people don't have one, and it's surprisingly nice to have, esp in the rain.