A while back, James Fee posted at length about using mapping tools for finding a house. One of the key things he talks about, and which we also experienced in tackling the same problem, is the ability to see many different types of info on a single interface: house candidates, schools, office location, etc. James writes favourably about Live's mapping tool and in particular the scratch pad feature.
Another site to add to your list if you are in the UK is OnOneMap.com. This basically takes many of these user needs into consideration and provides a number of layers: houses for sale, sold, schools, supermarkets and cell phone masts. In addition, you can require that the property be within a certain distance from a tube station, railway station or motorway junction.
Below is an example of search in London.
While in the process of house hunting in Seattle, I've been wondering how social media could help. Real Estate is an area with huge information asymmetries, but they are often between those with whom you might interact in a social media setting (other buyers and sellers). Perhaps a simple thing to do would be to have some review content for schools integrated in here.
StreetAdvisor is another new site which may be able to help in this area. They provide an interface which allows you to identify a street and then review it in both a structured and unstructured format. Currently, it is not highly populated, but if it takes off I can imagine it would be very valuable.
Finally, just like James, I looked at using SketchUp as a way to present my house.