If you have a Magic Mouse, you need to download MagicPrefs—it lets you fully customize gestures, swipes, touch sensitivity and, crucially if you've got a 27-inch iMac, double the tracking speed. It's free. [Apple]
I'd love to know why there's so much work done on the magic mouse and not so much on the MT trackpad.
to my memory you have, bettertouchtool (no support for thumb resting) and JiTouch the beta which I currently rate better that btt which have support for magic mouse as well