Dungeons And Dragons Online: Digital Map Projection

If you can afford it, someone has come up with a really cool means of mapping pen and paper games to tabletop:

I scan in adventure maps and Photoshop out all for the DM-only information (room numbers, secret doors, traps, etc.) and create a mask layer. We then suspend a digital projector (connected to my laptop) from the ceiling, pointing directly at the game table. I project the edited map onto the game table and scale it to match our miniatures. As the players explore the map, I erase portions of the mask layer, revealing the map beneath.

The site includes pictures of the setup in action. As this was spotted on Slashdot, the site may be suffering some slowdowns.