Free 411

If you call 1-800-FREE-411, you can get directory assistance for free. You have to listen to an ad before you connect and then an ad before you actually get a number.

Update:
I just tried this and it did work, and didn't take long at all. It is voice automated so you have to keep the children quiet or it won't let you do it. They mentioned that if you need to speak to a live operator then you can sign up on their website and then when you call in you can speak to one.

I usually use 411 in the car so this would be great, but if I am in the car I usually have the children. Wonder if they can not talk for two minutes?