So I"ve had one of those usb keys for nearly a year now and what"s on it? Nothing... so I decided to install Linux on it. 256MB should be more than enough and I would be able to boot it anywhere, use it for troubleshooting and impress my friends and co-workers. Upon doing a little bit of googling I found several distributions that aim to allow you to run a full-fledged Linux distribution on your usb key. Most of them are based on stripped down versions of existing distributions, most prominently Knoppix. Others are built from scratch.