- One finger click - this is the most common, of course - clicks an item/object/icon; do it twice to get a double-click, of course
- Two finger click - this is one I've wondered about for a LONG time - gets you the 'context menu' for the thing you click; I'll probably be using this a lot for LastPass
- Two fingers left - back (in web browser, at least Chrome)
- Two fingers right - forward (in web browser, at least Chrome, if there is 'forward' URL history)
- Three fingers left/right - rotate through Dashboard, Desktop, and any maximized windows; note that the fingers have to be lined up with each other horizontally
- Two fingers up or down - scroll; my current settings cause it to act like moving the scrollbar's "thumb" in the direction the fingers are moved
I believe some of these are app specific, and some probably can be changed in settings, but I haven't gotten that far yet.