Synergy2

Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware. It’s intended for users with multiple computers on their desk since each system uses its own monitor(s).

So I just installed this today on my Windows XP machine, Gentoo box, and also my Powerbook. And this thing is damn slick. I would suggest to everyone with multiple machines to install this. Especially when you have a desk with your laptop and main machine on them. Only think that I am seeing is that the “spacebar” doesn’t seem to work 100% right away. Somewhat of a lag.  You can download the setup programs and such from their site here.