Mouse gestures are a means of controlling your computer by stepping your mouse through a series of movements. FlyGesture is free Mac software that lets you create your own mouse gestures to control the Mac.

I first encountered mouse gestures in the Opera browser, where you could, for example, close a tab by moving the mouse to the right, then down and to the left on a diagonal.

From the developer's Web site:

FlyGesture is activated like Exposé or Dashboard, bringing up a transparent window of "guides" to move your mouse through. Moving your mouse through the guides lets FlyGesture know what action or actions you want to be performed, such as closing a window or opening an application. Not getting it? Here's a movie that demonstrates creating and using a new gesture to open Safari.

You can use FlyGestures to type text, call command keys, open files or folders, open Websites, run Automator workflows, run custom AppleScript, and more.

I gave FlyGesture a whirl -- as productivity maven Merlin Mann notes, "this is just a really pretty application". It's well-designed, and easy to configure.

I don't think it's for me, though. I'm a writer, which makes me a keyboard guy. I can't imagine I'd be able to remember which mouse gesture does what. I use the mouse as little as possible, and I use Quicksilver to drive the Mac using my keyboard. However, if you're a mouse person, you might love FlyGesture.