monline

iTALC is a free (GPL) remote control solution primarily targeted at teaching and education (controlling a number of clients at the same time, broadcasting teacher's screen to students, etc.), however it can be also used as a replacement for VNC. In my old Windows-user days I've found NetOp to be a lot more effective remote control solution (regarding speed and usability), than the free VNC. I've read somewhere that iTALC is a free replacement for NetOp, so go and try it.

I've just found Synergy, a solution for easy parallel access to the desktop (screen, mouse, keyboard) of multiple workstations. It's a wonderful piece of open-source and free software. Unfortunately it does not support Windows Terminal Services, but it's still a masterpiece.