As long as we're pimping cell phone products, here's a free one that can be used from ANY phone and might be a big money-saver for you: 1-800-FREE-411.
I haven't used a paper phonebook in years; if I'm near a computer, I can be at Switchboard.com in a jiffy. For the same reason, I never use 411 at home or work.
But I use "directory assistance" on the road all the time, and the charges add up rapidly.
1-800-FREE-411 is an advertising-supported service that will look up any number in the US for you for free; the "price" is that you may have to listen to a brief ad (15 seconds or so) before you get the number you're after.
Obvious tip that it took me a few minutes to figure out: Save the number in your cell's phonebook with the text name "411 Free," and it'll alphabetize to the top of the list.