I read on the iMac list that you can run OS X on an iMac. And I'm inclined to secure one from Bruce (yep, he has one -- a 266 MHz, the first iMac, I believe) and try to load the X. Hopefully I have OS X on CD and not DVD (have to check on that). It might be too slow, but the lure of running X with Safari is too tempting.
But it looks like you need a newer iMac to run OS X effectively.
Update: Yep, this tray-loading iMac 266 runs some flavor of OS 8, and besides needing an 8 MB disk partition to even start trying to run OS X, it's probably not wise to take it past OS 9.