[Sigia-l] info on neighborhoods in u.s. cities

[Frank Shepard]

Hello,

A client wants to expand the local search functionality of their site
by allowing users to expand the radius that defines the result set.
They currently do this in terms of distances (miles) but would like
the list of options to include a list of "surrounding neighborhoods."
(Yelp.com offers this functionality on their site.) This would require
a list of neighborhood names in U.S. cities (which I have located) as
well as some way to determine their proximity to a given point (maybe
a zipcode). Does anyone know if this information is widely available,
either free (e.g., from the post-office) or otherwise? Is there a
standardized government list associated with zip-codes?  Does anyone
have any suggestions? Your assistance is much appreciated.

Best regards,
Frank Shepard