Brightside is a tool to add reactivity to the corners and edges of your GNOME
desktop.

Brightside provides edge flipping to allow you to switch to the adjacent
workspace simply by pressing your mouse against the edge of the screen.

Brightside also allows you to assign configurable actions to occur while you
rest the mouse in a corner of the screen.

-- Brightside Homepage

WWW: http://catmur.co.uk/~ed/main/brightside/