I have spent many many hours searching the web for what seems to me to be a simple thing with no luck and lots of frustration.

What I'm looking for is a reverse phone book lookup. that is: I send a phone number and I get back correct address information for that phone number.

This must be a free service of the United states Postal Service. I can't distrivute an application that includes a pay-for-use service

I can't even find a listing of XML web services that is useful (one that lists by service provided rather than company).

Does anyone know of a (non-commercial) listing of web services by information provided rather than by company providing it? And, mor specifically, a reverse lookup (phone number to address)?