Here's an interesting feature of iPhoto that I'd never heard before, courtesy of Mac OS X Hints. While using Edit mode in the app, you can drag two fingers on your MacBook's touchpad (or your Magic Trackpad) to control the various edits with better precision than just dragging around a mouse. You can zoom the crop feature in or out, or even control it manually by dragging two fingers around. And you can rotate the photo in straighten mode just by rotating two fingers around the trackpad.
There are more of these little gesture features hidden in Apple's iApps (like a three-finger swipe in iPhoto to move forward/backward through photos), and I'm sure we'll see a lot more of this pop up as w
