Damm Small Linux (DSL) was originally developed as an experiment to see how many usable desktop applications can fit inside a 50MB live CD. It was at first just a personal project, ut over time Damn Small Linux grew into a community project with hundreds of development hours put into refinements such as a fully automated remote and local application installation system and a very versatile backup/restore system which can be used with on writable media including hard drives floppies or USB devices.
Version 3.3 has just been released, get it while its hot.
Downloadcurrent.iso