I just impulse bought a Mac Mini G4 - the 1.50ghz with the 64mb Radeon card.
Anyway, I'm going to take it apart and upgrade the hard drive, RAM, replace the coin battery cell, and then plan to configure it for triple boot - OSX/MorphOS/Gentoo.
I also plan to do some fun experiments in each of the OSes. I'm considering blogging this, if people think it'd be useful, but don't want to invest the time if nobody cares. Let me know if you think this would be of interest.