With a LiveCD, you have an entire system contained on the CD and with that, the freedom to do nearly anything that a system installed on your hard drive can.
GeeXboX is not an application, it’s a full-featured OS, that one can boot as a LiveCD, from a USB key, an SD/MMC card or install on its regular HDD.
MoviX can boot from CDs, HDDs, USB Flash Drives, CompactFlash cards and network. MoviX2 is a spin-off project that features X alongside the usual MoviX configuration.
It can turn your computer into a kiosk-like station by leveraging web technologies, making surfing and watching movies as easy as pie.
PTS Desktop Live is designed around the Phoronix Test Suite with the operating system itself consisting of a stripped down Linux environment, then built upon that is the Phoronix Test Suite with its test profiles and suites.
Crunch Bang is a Debian GNU/Linux based distribution offering a great blend of speed, style and substance. Using the nimble Open box window manager, it is highly customizable and provides a modern, full-featured GNU/Linux system without sacrificing performance.