I've discovered a great online source for telephone directory information. I consider it MUCH better than the other directory search engines. It's:
http://yellowcom.addresses.com/

This directory search engine provides:
(1) White page lookup
(2) Yellow page lookup -- by category or business name
(3) Reverse Phone Lookup -- gives the name and address for a phone number of interest
(4) Reverse Address Search -- gives the name and phone number for an address of interest
(5) Reverse ZIP-Code Lookup -- gives the city for a ZIP-code of interest
(6) ZIP-Code or Area Code Lookup -- gives the ZIP-Codes and Area Codes for a city of interest

After doing a search, most directory search engines (Superpages, Switchboard, AnyWho, Zip2, etc.) require that you then click on something to do a secondary search to find the phone number for each INDIVIDUAL hit. This site DOESN'T require those secondary searches!

Your first search with yellowcom.addresses will display both the address and the phone number for most all of its hits. This feature alone makes this source especially handy. This can be a BIG time-saver, especially if you're trying to collect a list of, for example, all the hardware stores or all the sign shops in an area.

Hope this helps.