Microsoft has released a free tool for managing multiple machines. It allows you to use one mouse and keyboard on multiple machines. It also lets you drag files between those machines.
Once you install Mouse Without Borders you get a control panel where you can adjust settings. Mouse Without Borders must be installed on both machines. Once you have given the client machine the name of the host machine and a security code that the first machine establishes you can then slide the mouse off the side of the host screen. The mouse pointer then appears on the side of the client machine.
From what I understand, it was created by a software developer at Microsoft, who built it on his nights and weekends. Interesting that Microsoft encourages their employees to do this on their nights and weekends, whereas Google generally give their employees a percentage of their work time to work on creating new products of which the employee envisions.
Mouse Without Borders can be downloaded from Microsoft here.