DamnSmallLinux

From LQWiki

Damn Small Linux is a bootable Live CD Linux distribution based on Knoppix which is compact enough to fit on a 50meg 'business card' CD. Despite its minuscule size it strives to have a functional and easy to use desktop. The window manager is Window Maker.

DSL is especially useful to carry in your wallet, just in case. For $5.50 the official site will burn you a copy, much less fuss than finding the tiny CD-Rs in small quantities. You can use a normal CD, but that somewhat defies the object.

Because the distro is only 50megs, most computers will comfortably run it from Ramdisk. This is much faster and allows you to put other CDs in the drive once DSL is running. Provided the machine has 128megs or more, type the cheat code 'knoppix toram' when prompted.