Damn Small Linux plus pendrive:

Interesting tiny little Linux distribution.“My conclusion: DSL is a great little distro. I can hardly imagine spending a day now without my trustworthy DSL-powered pendrive. Pendrive-based distros beat live CDs because they let you quickly save your session preferences and data on the same medium as the operating system. I won’t use live CDs anymore except on older systems that don’t support booting from a USB device, or for trying new distributions.” Linux.com | Damn Small Linux plus pendr