Trackpad Gestures
this post is really more for people with magic mice and the trackpad that comes with all the mac laptops. Alot of time and technology has been invested to make the trackpad respond to multi-touch gestures.
I really appreciate these little touches (ha ha bad pun intended) because I've always found the placement of the expose button slightly awkward because I have to lift my hand to find it on the keyboard (That's F3 on the keyboard for you, you may thank me later. Lion users you're out of luck here!).
A few gestures of note -
Two finger scroll - scroll up, scroll down. Easy peasy.
Two finger pinch in/out - Zoom out and zoom in (in that order)
Three finger swipe - Differs from application to application. For Finder, Safari and other web browsers, it mimics the forward (Three finger swipe RIGHT) and back (three finger swipe LEFT) buttons.
Four finger swipe up - Show desktop
Four finger swipe down - Expose
Four finger swipe left/right - Call up the application switcher
It's a little complicated to imagine what I'm going on about exactly, but hit up System Preferences > Trackpad, and they have a nice little video for each gesture for you to see how exactly it's done!
Any other suggestions or frequently used gestures? Let me know and I'll do another update on this entry!