If you’ve got a multi-touch gesture enabled Apple notebook computer, you should take a look at the MultiClutch preference pane from Will Henderson. This preference pane lets you assign multitouch gestures (like Swipe Left/Right, pinch, rotate) to keyboard shortcuts on a per-application basis. You can also assign these gestures to global system-wide keyboard shortcuts. This lets you take gestures that normally only work in Apple applications, like swipe left/right for forward/back in Safari, and use them in other applications like Firefox. In the screenshot to the right, I’ve taken swipe up/down and set it to switch between tabs in my iChat chat window.
This feels like the type of thing that should be built into the system, but until it is, Will Henderson has provided an excellent (and free!) tool.