Have you ever wanted to share one keyboard and mouse with multiple computers? Sure, you could buy one of those KVM (keyboard-video-mouse) switches and wire it all up, but there's no need for that when you can just install Synergy.
The beauty of Synergy is that it works over your network, and it's available for multiple platforms. No new wires to mess with. Just install the software, set some parameters, and you're off and running. Drag your mouse off the edge of the screen on one computer and it instantly appears on the other. Boom!
And that's just the beginning. Want to copy text from one computer to another? Synergy supports that. The developers are even working to support file drag-and-drop between systems. How cool is that?
If you have multiple computers at your desk, skip the hardware KVM (or worse yet, separate peripherals for each) and get Synergy.