I'd be glad to relieve you of this burden... ;-)
Actually I've just resurrected an old PowerMac 9500 (nearly as old as the last A4000Ts) I got for close to free with an absolutely fantastic Sonnet Crescendo G4 1 GHz ($99). Also having expanded the RAM to 248 MB, OS X (10.2) runs pretty well on this ancient machine. Could use a bit more RAM, but for my fooling with OS X and BSD it's quite enough (the Mach32 graphics sucks though).
A Mac Mini should run pretty nicely - if low on RAM, just throw it some more, it's nearly free nowadays.