Found this doing random browsing after doing too much calc at 2am. I don't think anyone here posted this yet. This is a link for an awesome one that use a rear screen projector. Either use one you have or build it and make the screen. Softmt.com Multi-touch software YouTube - My home made 60 inch multi touch screen ! there's a bunch of apps for it as well, thinking of doing something with an extra 17inch LCD I may soon acquire back.