Keymo for Mac

From Many Tricks:

Keymo gives you full control over your mouse via the keyboard. You can build custom actions to move the mouse by a specified number of pixels at a time, move it immediately to a screen edge or corner, move it to another display, move it to the center of the screen, scroll windows with scrollbars, and even click and right-click (with modifier keys optionally passed along). One of the cooler features is what we call move by division: this sub-divides the screen by half each time you invoke it, which makes it really easy to move across huge swaths of screen real estate with only a few keystrokes.