On my *dead* P5B I've got a Swifty MCX solid copper block on the NB which is by far the most awesome cooler I've seen for NB cooling. And I've got an Extreme Spirit 2 on the SB, also another nice cooler but the mounting system is a bit wonky. The Swifty is much more solid.
Asus Sabertooth 990FX | AMD Phenom II X6 1090T | 16gb G.Skill Ripjaws X DDR3 | Thermalright Silver Arrow
2 x Sapphire HD 6870 1gb CrossfireX | LG 10X Blu-Ray Rewriter | PCP&C Silencer 750 Quad | Fractal Design R3 Case
60Gb Patriot Pyro SATA III SSD | 1Tb WD Black | 3 x 2Tb WD Green | 2 x 360Gb Seagate Barracuda