Synergy is a free software
tool which allows you to share a common keyboard and a mouse between
multiple computers on a local network (Linux, Mac, or Windows). Synergy
also lets you share Clipboard contents between different systems. It’s
essentially the perfect solution for someone working with multiple
displays (and operating systems) on a cluttered desktop.
Tutorial Video:
The only requirement is of a local network connecting all the
computers together so you can define one computer as a server and the
others as clients. The “server” computer has the keyboard and mouse
physically connected to it. Other computers that will share the keyboard
and the mouse are the “clients”.