Scythe Ninja Rev.B CPU Cooler @ PureOverclock
 

This one is no doubt going to be interesting as not only is the Ninja Rev.B built specifically for low airflow, low noise usage, but Scythe claim it is such an efficient heatsink -what with its 12 heatpipes and huge surface area- that you can fling the fan across the room and go "passive.

Scythe Ninja Rev.B CPU Cooler @ PureOverclock