Two toll free directory assistance providers offer absolutely no charge directory assistance service across the United States. I have found these very useful, especially with a mobile phone. Using them means you don't have to pay $1-2 for directory assistance through your local or wireless phone carrier.
Both are advertiser-supported - you listen to a 15 second ad before you get your number.
1-800-FREE411 - This one will give you a short tutorial the first time you call (it remembers your phone number), so the first time you use it, it might seem a bit ponderous. Subsequent calls work faster. This one is usually completely automated, recognizing your voice commands. You usually never talk to an operator.
1-800-411SAVE - This one is slightly faster because it relies on human operators who take your inquiry and then an automated system reads the number (along with a short ad).
BTW, you can get news headlines, sports, movie theater times and other related information 24/7 using a free automated service - TELLME. It is on 1-800-555-TELL. It recognizes your location by your phone number, saving a lot of time for things like local weather, movie times, and the current time. The system is completely automated.
All of these are toll-free (airtime minutes from mobile phones are still deducted however)!