Generally, you need some sort of hardware to share a single keyboard / mouse between different machines. However, Synergy software lets you share a single keyboard, mouse, and clipboard between machines without special hardware. It's intended for users with multiple computers on their desk since each system uses its own monitor(s).
It is common practice to run Windows XP and UNIX boxes side by side for various reasons. Synergy is open source and released under the GNU Public License (GPL). It works with Windows, Mac OS X and UNIX operating systems.
In the following example, the user is moving the mouse from left to right. When the cursor reaches the right edge of the left screen it jumps instantly to the left edge of the right screen. Do you wish you could cut and paste between computers? Now you can! Just copy text, HTML, or an image as you normally would on one screen then switch to another screen and paste it. It's as if all your computers shared a single clipboard (and separate primary selection for you X11 users). It even converts newlines to each computer's native form so cut and paste between different operating systems works seamlessly. And it does it all in Unicode so any text can be copied.
(Fig 01: Synergy software in action ~ sharing mouse between Windows and Linux KDE desktop (image credit: Synergy project] )
=> You can download synergy software here.