In the really-cool-free-utilities category is Synergy. If you have more than one computer on your desk, with a forest of keyboards and mice, then you need Synergy!

Synergy lets you easily share a single mouse and keyboard between multiple computers (even with different operating systems), each with its own display, without special hardware. Your (single remaining) mouse can roam a single logical desktop area, moving seamlessly and effortlessly from screen to screen. Which ever screen your mouse is on is where keyboard typing will go. You can copy to the clipboard, move the mouse to another monitor, and paste, and it works! It also works where existing computers already have multiple monitors. Nice!