I've been reviewing some of the emerging web 2.0 real estate tools recently, over here. I just took a look at Propsmart. It debuted recently and is loaded with features for buyers and brokers. Propsmart revolves around the phenomenally successful and amazing google maps application. Just enter a zip code and see what happens. Cool!
Here's last week's Wall Street Journal review of Propsmart. And last month's review in the Kansas City Business Journal.
Accounts are free. Get one!