Google launched last week a directory assistance service that uses voice recognition to automatically answer queries about the US local businesses. The service is free, but if you're not in the US or Canada, it's not very easy to see how well it works.
Fortunately, Yahoo Messenger lets you call toll-free US numbers that start with 800, 888, 877, or 866. This is a fairly recent feature that was added in Yahoo Messenger 8.1. All you need to do is call 8004664411 and follow the directions.
Skype also offers free calls to toll-free phone numbers, but Google's number is always busy.
If you discover some interesting bugs or funny answers, record the conversation using a software like SoliCall or Audacity*, upload it to odeo and post a link in the comments.
* Most sound cards have the option to record mix that captures the output signal from wave channel AND input signal from microphone channel. In Windows XP, go to Start/Run, type sndvol32 and in Preferences toggle the "Recording" option and select "Stereo Mix" (make sure you select in the main dialog as well). Then you can record the sound using with Audacity or other audio editor.