I hosted "Picks from the App Store" on Ustream.tv on April 29, 2009. The broadcast was recorded live and you are certainly welcome to watch the archive version below or at ustream.tv/recorded/1445088.
The best part about the broadcast was the associated chatroom. Unfortunately, the chatroom was not archived with the video. During the hour-long workshop, I demonstrated and talked about a variety of apps. Here are the App Store links:
In addition, after the show I learned that you can indeed search within the iTunes Store for only free apps. After initiating a search, click Power Search and select Applications. You'll see a checkbox that says Search for free applications.
Note: Unfortunately, the recording did not pick up the audio or video from David's call--another reason to watch live.