I noticed a blurb in the June 19th issue of Time magazine that says Zillow.com has estimated values for over 65 million of the 85 million single family homes in the U.S.
Just enter the street address, city/state or zip code and find out what they think a home is worth.
I noticed the information for some homes is not updated to include updates that have been done since the time the house was last listed. Zillow.com claims an error rate of +-7.2% from the median value, but the Time blurb says any single estimate can be wildly off.
If nothing else the site may give you an idea of what homes may be worth in a particular neighborhood.