coolbits for me as well. there are other programs like rivatuner and powerstrip, but they are standalone. as wentelteefje stated, it'll get integrated on the nvidia driver control panel. and it unlocks lots of hidden menus. one in particular which i like (besides the OCing menu), is the "tools" menu. it has something called display optimization wizard, so if you have a lcd, it'll correct the display and to me, it does a LOT better job than pressing the auto-adjust button.
EDIT: coolbits is a registry tweak. forceware is the nvidia drivers.