Turn One Computer into Two
 

Userful® (Free 2-User Edition) is a simple and free way to transform your dual-monitor PC into a dual-station PC! You'll be able to support two independent users, each with their own screen and keyboard with just one PC. All you need is a computer with two monitors connected (e.g., using a dual-head video card) and an extra USB keyboard and mouse.

http://userful.com/products/free-2-user

Imagine how much a elementary school will save from 40 PCs in a classroom down to 10 or less; nice concept, needs more apps and testings.