SliTaz

SliTaz GNU/Linux is a free operating system working completely in memory from removable media such as a CD-ROM or USB key. It is light, speedy and fully installable on a hard drive. SliTaz is distributed in the form of a LiveCD that you can easily burn to a cdrom and boot from. When the system is running you can eject the LiveCD and use your CD drive for other tasks. The Live system provides a fully-featured, working graphical distro and lets you keep your data and personal settings on persistent media. The system can be extended with the Tazpkg package manager and security updates are provided for the cooking and stable versions.