Few things do a better job at decimating desktop real estate than a bulky old flatbed scanner. Skinnier replacements are cheap these days, but what's one to do with the old ones? An enterprising hacker who goes by the handle Sprite_tm, the same bloke who brought us a knock-operated door, has managed to create a multitouch panel out of his. He extracted the single-line CCD and mounted that below the display. He then attached five LEDs above it to shine light down. When his finger touches the screen it casts a shadow on the CCD and, with a little (probably a lot) of custom software he's able to triangulate the position of the touch. The system even works with multiple fingers, though we're guessing should they overlap vertically the system might get a little finicky. Check out a demo below and then click on through the source link for one heck of a detailed how-to.