Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems without special hardware. It's intended for users with multiple computers on their desk since each system uses its own monitor(s). Just move the mouse off the edge of a screen to move to another screen; keyboard and mouse input is then redirected to the other screen. Synergy also lets you cut and paste between systems and it makes screen savers activate/deactivate in concert.
