If you are looking at a specific company as far as cards, VisionTek seems to be putting out some nice cards. I got my visiontek xtasy 9500 pro up to 405mhz/330mhz. That was using a 1U server cooler. Using the stock cooler and nanotherm blue II thermal compound, I was able to pull 385/310.
The new 9600's seem to be doing very well in terms of OC, might want to check into one of those.