If you've ever wanted a KVM switch, forget about it. Synergy, an open source tool, replaces a KVM with a free software solution.
A software-only solution, it communicates across the network instead of through dedicated cables, so you can reduce your cable clutter.
Simply tell the configuration where the computers are located relative to each other (i.e. "laptop is to the left of desktop and desktop is to the right of laptop.)
As soon as the mouse passes the edge of the screen, it goes to the other computer mouse and keyboard now act on that machine. As I write this post my laptop's external monitor is to the left of my desktop, and my server monitor is to the right of my desktop monitor. One sweep of my hand and my mouse passes across all three monitors.
You can even cut and paste across computers. That feature is a little buggy, but that's the worst thing I can think of to say about this little gem.
If you're using Vista, be sure to set AutoStart to "When You Log In" instead of "When Computer Starts". You may also need to disable UAC. I haven't tried it on Windows 7 yet, but I'm going to guess that the same would hold true.
This would be worth real money, but as open source, it's free, so just enjoy it.
You can download Synergy for free here.