Crisp and I have just finished an upgrade to the Undercroft for the Dungeons and Dragons sessions.
We've installed a second projector pointing down so that they can lay a white board over the coffee table and have the maps from the Dungeon Master's laptop projected on it. This way they can move their little miniatures around on the map and the DM can change the map as events warrant.
It's just a super-cheap projector from China, but it does a pretty good job. It's mounted on one of my patent, over-engineered, vibration-isolating mounts using rubber o-rings to stop the dance class upstairs shaking it too much ;)
I think it'll be a hit with the gang when they come tomorrow- I'll try and post some better pictures of it in action then :)