Multi-Touch mini
I’m sure you’ve all seen Microsoft’s surface technology or the ‘big ass table‘ which shows how useful multi-touch can be. However if you don’t want something the size and cost of a small car then you should look at the MTmini. All you need to make a multi touch is a cardboard box, a piece of transparent material (glass, acrylic or plexiglas), Paper, USB Webcam, Computer, Pictureframe (this is useful to get the glass from).
You can download all the software on their website. The video below shows how it works: