Where can I find a list of all the neighborhoods for all the US cities?

Downloadable database is preffered.



Look:

http://en.wikipedia.org/wiki/List_of_neighborhood_listings_by_city



See the US section.

When you select one of the US cities, you get a list of neighbourhoods for the city selected.



This list is what I need for ALL cities, prefferably as a downloadable database.



Such a database must be several times smaller than a zip codes databases (which are for sale on every crossroad in the web), so I don't think that this is something like an attempt to "download the internet".



Any ideas on where can I buy such a neighbourhoods database?Where can I find a list of all the neighborhoods for all the US cities?
http://www.city-data.com/Where can I find a list of all the neighborhoods for all the US cities?
The Homeland Stazi Agency

The New FBI

They have some.