I know these people...
jodyjohnson said:
www.projectorcentral.com
Use Calculator Pro
Check to make sure your projector can focus at short range (ours is about 4' max, or 5' with a mirror). With a mirror we also are looking for a ceiling mount (vertical flip) and rear projection (horizontal flip).
It will also give image size at your target distance. Our target for selecting a projectors is 30"x40" at 5' (50" diagonal). This gives enough room for the party to see up to 12" (60') in all directions (darkvision range, lowlight w/30' light source).
Sorry I'm so late posting here. I wasn't aware of this thread, so I started on page one and it's taken me awhile to read to page 5!
I bought my projector from these folks. A friend of my wife's works at projectorpeople.com. (If you call, ask for Carmen; tell her Frank of "Frank and Beth" sent you!

Maybe that'll save you money, maybe it'll cost you more. No guarantees from me!)
I bought a NEC LT240K. With the screen to project onto (I'm using it for movies and playstation, too) it cost me about $2k back in December '04. It was my Christmas present to myself, and I didn't get anything else.
I've got a pool table upstairs, so I've been moving the projector around each session, trying to figure out how I want to do this. Hanging it above the table would be tough because I put a ceiling fan there.

But I'm going to look at putting a shorter drop-shaft on the fan and gaining another 4"-5". Maybe top projection would work after that? I also thought I might put some kind of reflective surface above the table instead of hanging the projector directly over the top, but that won't work without a honkin' big mirror because this projector has a pretty big image with a short throw distance.
I would recommend this projector, but compared to prices that Steel Wind has posted, I would want a better deal nowadays. Still, it has two VGA inputs, component, DVI, and S-video. And a USB port so that the remote that comes with the projector can be fed back to the laptop to control the mouse! This is *cool*! The projector's remote has a simple "paddle" on it that can be pressed in 8 directions and the projector sends mouse events to the laptop. Combined with the laser pointer built into the remote, that's about all we need.
I use Tabletop Mapper, as Steel Wind mentioned, but I've found it too slow for what I want to do. He didn't mention this (so far in the thread), but it has the ability to keep track of PCs locations and automatically do LoS calculations and expose pieces of the map that the characters can actually see (you put in sight distance for each character). However, it's written in VB and it's not fast enough on my Sony 1.6GHz PentM.

I'm rewriting it in C++ and adding some other features. Since I don't really like Windoze, though, I'm writing it using the Qt3 framework so it'll compile everywhere (Qt is a free cross-platform GUI library). I'll post here when it's usable...