The wallet contest @ instructables is really getting some great entries, ineluctable writes -
Mountain Bike Tires are cool. If you’re like me, you always have a few extras around that you can’t quite throw away, because well, they’re so cool. Now you can have a wallet that is as cool as a knobby mountain bike tire. And if you go for the optional drop sensor, when you’re getting down and funky in the club and drop yer wallet in the dark, a series of flashing lights will tell you exactly where it hits. Also fun for just projecting flashing lights when you smack it against stuff, or people.
instructables : Knobby all terrain rubber wallet with optional smack-lights (Drop alert sensor) – Link.