Do you often use a desktop computer and your notebook side-by-side? Do you hate switching the keyboard and mouse only for quickly replying to an email on the notebook, or for quickly checking a logfile on the desktop computer?

There is a free and easy solution to the problem on Linux and Mac: Use Synergy. It is a small and effective TCP/IP-based client-server application that lets you share keyboard and mouse of one machine with another one, with slide transition of the control via mouse movement just as with multiple screens in cinerama mode. This is much more handy than using a KVM-switch, as it doesn't require to switch off the screen of the other computer, and even allows for sharing the clipboard!

A short and good tutorial is available at a March 2009 article on LinuxMag.