Back and forward through browser history for starters.
I switched it off though. It's not reliable enough for me (may be due to the settings I've used for 2 finger sensitivity).
I agree, the fixed driver works incredibly well. Beware though. It spoils you. I had to fix my SIL's toshiba the other day, and was constantly pained by its lack of scrolling. Everything I did was slow and inefficient, and I had to have 3 goes every time I needed to scroll:
Swipe. *Huuh? Oh, that’s right!*
Painstakingly navigate the cursor to the scroll-bar, click and hold button with left index finger, scroll.
20 seconds later, repeat!
Getting back to my mini with meklort's sublime trackpad driver was sweet, sweet relief!