To find the right camera for real estate, I suggest heading over to dpreview.com, scroll down to Buying Guide and click Feature Search.  Then under Zoom Wide(W) choose <=24mm.  Every camera Frank suggested except the V570 Frank used to shoot the video is on the list.  When I checked just now, there were two pages of cameras.  This is amazing because just a few years ago, the V570 and V705 were the only two compact digital cameras with sub-28mm lenses.

That Leica X1 looks great, but for nearly $2K it better be great.  Coming down the price scale and my next recommendation is the LX3 in the $500 range.  Beyond that, any of these cameras should do a great job.

I used a Coolpix 5400 for years.  I do have a wide angle adapter for it because that was my best option at the time.  I find that wide angle adapters for compact digital cameras have really crummy optics and often suffer from sever barrel distortion.  What I'm saying is that if you have a wide angle adapter, use it (You can correct for barrel distortion in software), but if you don't already have one, keep saving until you can purchase a camera with a wider lens or even better save up for the DSLR and ultra wide lens (10-22mm or so).