brightside: workspace switcher
This utility for the GNOME desktop allows you to switch between virtual desktops by moving the mouse cursor to the edge of the screen, as if dragging it to the next one beside it, and is a nice alternative to keyboard shortcuts for the more mouse-oriented user.
The configuration screen in the screen capture can be started by running the command brightside-properties. The command may also be in the System->Preferences under Screen Actions. To activate brightside when you log in, place the command brightside in the Startup programs list in System->Preferences->Sessions.
You can also assign actions to the corners of the screen such as stopping the screensaver or running your favorite mail client.