Synergy combines your desktop devices together in to one cohesive experience. It’s software for sharing your mouse and keyboard between multiple computers on your desk. It works on Windows, Mac OS X and Linux.
When I was using my MacBook Pro, I had it hooked-up to 2 external displays and I used the MacBook Pro display for non-critical stuff like IRC and Twitter. Since I’ve stopped using my MacBook Pro and returned to my Linux desktop, with just the 2 displays, I’ve found that I really miss having a 3rd display (I know, it’s a First World problem).
So, this morning I installed Synergy on my desktop and an old ThinkPad. I now have 3 screens, again, and I’m super-happy with the result.