Ok, well I have an iMac G3 Slot loading computer in my room that I do almost nothing with. Any suggestions? I'll use it every now and then to play a DVD on.
(Sorry if this isn't completely vintage... but it is old, eh?)
I just bought a 400mhz G3 slot-loading iMac for $25 at a local university surplus sale last month. It had been stripped of both RAM and a hard drive, but once those were replaced, it has proved to be a capable machine. What I have done with mine is install Ubuntu Linux PPC (OS X would be too slow) on it with the intention of making it a "public" internet terminal for my living room. The slot-loading iMac is especially nice for that purpose because it's fanless and therefore relatively quiet. Right now, though, I'm playing a long game of Freeciv on it mostly.

I tried to make the iMac dual-boot.. there is a small OS 9 partition on it somewhere that I installed first, but after installing Ubuntu I haven't been able to boot OS 9 again. I've never done dual boot on a Mac before. Seems like it's not as easy to pull off as on a PC (either that or I'm just not that familiar with the process on a MAC). Ubuntu's boot loader seems pretty weak anyway.
Download the PowerPC version of Ubuntu
here. Note that the live CD version has a problem with X video settings for thte slot-loading iMac, so you have to manually change some of them after you boot to get the GUI on the live disc to work properly. The live disc also needs a lot of RAM. But if you just install Ubuntu to a HD then all of that is no problem.
Good luck! Let us know what you do with it.
RedWolf