My latest project has been to load and run Debian GNU/Linux on a Power Macintosh G4/466. The box came to me with no disk drives and 128 MB of RAM. I upped the RAM to 384 MB, and I installed two hard drives.
I really wanted to see how the G4 would do with OpenBSD, but while I was able to install it on two occasions, on neither of those was I able to get the system to boot. The regular FAQ for OpenBSD has excellent instructions on how to install it on an i386 machine, but the supplementary material for doing the install on MacPPC was less than helpful (or not helpful enough to get the system to boot).