MorphOS is a lightweight, highly efficient and flexible desktop operating system. It includes primarily proprietary as well as open – source components.
Here is a list os hardware requirement/compatibility – http://www.morphos.de/hardware
If you have an extra PowerPC machine and you are looking for some challenge go forward.
Download link -http://www.morphos-team.net/
You guys know the drill, before you try anything, please, make sure to back up everything important or everything.
P.S.: Files: http://morphos-files.net/index2.php