Synergy is software that givens you a virtual KVM, but just the keyboard and mouse. This fantastic if you have a nearby computer with a monitor you can see, but you don't want to have to switch to a different keyboard or mouse.
$ sudo port install synergy
Or, download the package installer from http://synergy-foss.org/.
Your "server" will be the computer that has the mouse and keyboard you will be using. The "client" or "clients" will be the computer that you want to control by the server. Here is a Mac example:
On the server
1. Open Synergy and check the box "Server (share this computer's mouse and keyboard)" at the top.
2. Click "Configure Server" under "Configure interactively"
3. On the "Screens and Links" tab, drag and drop a computer from the top right to the left or right box next to your computer in the middle, and name it.
4. Hit "Ok"
5. Then hit "Start"
On the client
1. Open a terminal and run:
$ synergyc 192.168.0.3
Where "192.168.0.3" is the IP address of the server.