Thought I'd pass on a tip I found at agentsonline.net.  Instead taking listing photos with a wide-angle lens, check out a university developed free demo program called "autostitch".  This program creates 2D panoramic photos by taking a series of shots and "stitching" them together.  The really cool thing is that you don't have to be careful about how you overlap the photos, or the sequence - it automatically finds the overlap points and seamlessly puts them together.  I did a test by taking several shots of my living room and throwing them into autostitch.  The result was fantastic -much better than I could have done with a wide-angle shot.  Here's the link for more info and to download:

http://tinyurl.com/5xa4o

Note that the author says you can use photos created by the demo version as long as you acknowledge the use of Autostitch.  You can also purchase commercial software that incorporates the technology.