I just stumbled upon these interesting mini fixed gear (or singlespeed) bikes on the internets. One is by a company called Airwalk Fixed Gear, and it’s called, rightly enough, the Mini Fixie.
The other one is the Sillgey Piccolo, which basically appears to be very similar, if not the same thing (I don’t know enough about either company to know if it’s actually the same bike). Either way, it’s a pretty cool little bike, and would probably work great if you lived a few flights up and had to carry your bike with you.
Update: I also found another one by Livery Design Gruppe (see below).
If you know of any others, please share in the comments section!