Mac: If you like to keep your hands on your keyboard as much as possible because it's faster and makes you more productive, then Keymo, a $5 app for Mac OS X, may be just the utility for you. The highly configurable app assigns keyboard shortcuts for moving the mouse, clicking, and other mouse actions.
It takes a little while getting used to, but developers Many Tricks offer a 1,000 uses free trial so you can see how the mouse moving works before buying. You can move the cursor in any direction by a specific number of pixels (good for precise pointing), move it to a corner of your display, or centre it on the screen. Move by division is pretty interesting; this divides the screen up into sections and moves the cursor into the centre of those increasingly smaller sections.
Perhaps the most useful of the shortcuts, if you have a multi-monitor setup, is the ability to quickly jump the mouse cursor to the other display. And if you ever lose track of your mouse because of all that screen real estate you have (or you just can't find it), Keymo can quickly highlight it for you in a spotlight, with a speech bubble, or an enormous mouse image.