Kent Sutherland, the developer of Chax, has released a preference pane called Warp that allows you to move through your different spaces with your mouse.

When Warp is enabled, holding your mouse to the side of your desktop will take you to the space in that direction. If you’ve ever dragged a window to a different space, you’ll be familiar with the mechanics of this. I always appreciate applications, like Quicksilver’s Abracadabra plug-in, which allow you to do everything without taking your hand off of your mouse. As I just started using a Wacom tablet as my main input device, small apps like Warp really make easy to keep my hands off the keyboard.

Check out Warp