Some silly ideas:
Socket 7 - MaxxMem Bandwidth
Slot 1 - wPrime 32m, dual setups are welcome!
Socket 370 - PCMark 2005, dual setups are fine
Socket 462 - Low-Clock challenge, 32M under one hour or similar
Socket 432 - Reference Clock
Socket 487 - 3DMark2001, any videocard, mobile CPUs with ct-479 are fine too =)
Socket 754 - Memory Clock
Bonus category:
SuperPi 1M on a CPU not produced by Intel, AMD, VIA (Cyrix before C3 is OK).