GeeXboX is a free embedded Linux distribution which aims at turning your computer into a so called HTPC (Home Theater PC) or Media Center. Being a standalone LiveCD-based distribution, it's a ready to boot operating system than works on any Pentium-class x86 computer or PowerPC Macintosh, implying no software requirement. You can even use it on a diskless computer, the whole system being loaded in RAM.
Despite his tiny ISO image size, the distribution comes with a complete and automatic hardware detection, not requiring any driver to be added. It supports playback of nearly any kind of audio/video and image files and all known codecs and containers are shipped in, allowing playing them through various physical supports, either being CD, DVD, HDD, LAN or Internet.
GeeXboX also comes with a complete toolchain that allows developers adding easily extra packages and features but that might also be used to give birth to many dedicated embedded Linux systems.