From Librarian in Black:
Free411 (1-800-Free 411 / 1-800-373-3411) is a completely automated free directory assistance service that works on cell and land lines. I know my cell phone carrier charges $1.50 for each directory assistance call. No longer will I fall for that!
Just call the number, give the city and state, choose whether it’s a business, government, or residential listing, and say the listing’s name. You’ll then start to hear a 12-second advertisement, which you can bypass by pressing a certain key (*cough* 2) on your keypad. The number is given to you twice. I tried it four times with four different listings in four different cities, and the voice-recognition software got each listing correct–even the number for our local library, which is notoriously hard to find for directory assistance. My only criticism is that it doesn’t auto-connect you like some of the directory services do. But hey, I’m thrifty enough to dial the numbers myself to save a few bucks.