I have the Thermaltake Volcano and it seems to be very good. Alot of people rave about the Swiftech MCX478. I am acutally thinking about getting one just to try it out. If your not doing very heavy overclocking you could probally just use the stock cooling.
Also the Dragon 478 is really good, and I have heard good things about the Sunflower, which looks to be about the same thing. But I think the Dragon pushes more CFM's.