I used to run x2vnc and win2vnc back in the MP3 days to let me control my Windows and linux boxen. Later I used the same setup with my old MacBook 15" and a Linux box. The other day, my friend n8 posted about his Synergy setup, which came perfectly timed. I just started a new gig at Bunkspeed and I'm using a dedicated desktop for dev instead of my MacBook Pro, but i don't want my Mac to be wasted. So i set up Synergy on both my home and work desktops and have the Mac on a stand running two Synergy clients (only one of which ever finds a server to connect to. This setup rules!
Update: Don't know if this is something i'll find a way around, but apparently logging on to the VPN killed the connectivity between my desktop and mac :(
Update 2: Ok, as simple as going into the Advanced config and telling it what local IP to listen for connections on. All good again