Idea Labs turned a 67" rear-projection TV into a multi-touch display, you can check out how they did it over here. The total cost of this project is $2,308.90, but the bulk of it ($1,857) was for the 67 Samsung HL67A750 Rear Projection TV.
Continuing our multi-touch research, wefve been working on turning an off-the-shelf rear projection TV into a multi-touch display. This screen has the best width-to-depth ratio of any multitouch system (67 diagonal viewing area and only 16 deep). This is also the first example of hacking a multi-touch system into an off-the-shelf television. The system we settled on uses very few additional components and could potentially be applied to any rear-projection TV.