Slax

Slax is a Live operating system based on Linux. Live means it runs from an external media without any need for permanent installation.

Slax boots from USB mass storage devices such as Flash Drive keys as well as from regular hard drives and CD/DVD discs.

Simply plug your device in and boot from it. Entire Slax operating system resides in a single directory /slax/ on your device, making it easier to organize with your other data.