Anything SMP using 386 or 486 CPUs would need a specially written OS/driver set for them so even if you found the machine pretty much nothing would run on it. I passed on a cheap dual P5 motherboard on ebay last year because while it looked interesting I don't think I would use it (I have a dual PPro overdrive system running Win NT). If I ever found a complete SMP 386 or 486 system running some kind of exotic UNIX I would jump on it just for the hell of it.

EISA is cool but 99% of the cards made for it are SCSI and Networking. I have a couple ATI 2MB video cards and another brand I forget now plus some video editing cards made by Matrox (one is EISA and the others are ISA, something like 4 cards connected to each other).