1-800-GOOG-411: Find and connect with local businesses for free from your phone.

I personally use this all the time. Phone companies are now charging up to $4 to get Directory Assistance - THAT'S INSANE! The Google411 Service is totally free and has a bunch of cool tools to go with it. But if you just need a phone number, this is the way to go. Listen to a super quick advertisement and that's your only cost.

From the Sites "Learn More" Page:

1-800-GOOG-411: Find and connect with local businesses for free from your phone.: "You don't need a computer, an Internet connection, or even the keypad on your phone or mobile device. GOOG-411 is voice-activated, so you can access it from any phone (mobile or land line), in any location, at any time. For free. (*)

Dial (1-800) GOOG-411. Say where. Say what you're looking for. GOOG-411 will connect you with the business you choose.

If you are calling from a mobile device, GOOG-411 can even send you a text message with more details and a map. Simply say 'Text message' or 'Map it.'"