I'm also impressed, and I'm harder to impress than Paul
My one suggestion would be to make the geographic searches a one-click deal. Instead of clicking on a state, or several states and then "Search", just link each state to search. I think the multi-state search is cool, but I'm a lazy web user, and the extra click takes too much out of me
. My guess is that the vast majority of your users will be searching within a small geographic area anyway.
But very cool and well done!