My setup in my office desk might look weird at first glance because apart from having 2 laptops, there is also an external keyboard and mouse (trackball)... normally you would just connect it to one laptop to control it... but would you believe you could also use it on the other laptop at the same time without having to replug it?
There is an application called Synergy... it is freeware... and supports many operating system platforms (Mac, Windows, Linux). Just visit the website, http://synergy2.sourceforge.net , to know more about it. The main requirement of this application to work is that both computers (laptops) are connected on the same network (both computers are connected to your router at home, the one connected to your internet/DSL modem). That network connection is what is used by Synergy to link the keyboard and mouse of both machines together. They could work even if the two machines are running a different kind of operating system, provided you install the proper version for the kind of operating system.
To explain a little further how this works, the keyboard and mouse are connected to the laptop on the left... I'll just set Synergy on how the orientation of the laptops are... so, when my mouse pans to the far right, the mouse passes to the laptop on the right... and it could go back to the other laptop on the left just by scrolling back to the far left.
The limitations of this however is that only the control of the mouse and keyboard is shared between the two computers and also when you copy-cut-paste text from one to the other... you cannot however drag a window to the other computer's desktop, or copy-cut-paste files from one computer to the other.
Since I am a Linux user... I will tell you an easy way to install it. Just type the following commands in a terminal window to install it:
sudo apt-get install synergy quicksynergy
This will install both the application Synergy and a GUI to control it (QuickSynergy).
Sorry if I am unable to post some snapshots of the application itself in action... maybe next time... If you are interested in this application and needs help configuring it... just post a comment and let's see what happens.