window manager - Multi-Monitor with multiple computers

I need to know if there's an free application that does the same as the MaxiVista "Extended Screen" functionality.

Basically is to use a 2nd computer screen as an extra monitor of the main machine. http://www.maxivista.com/multi_monitor.htm

This is different from Synergy or Input Director that "only" able to manage multiple computer with a single mouse/keyboard.

Thanks! Alex