Public Radio Tuner (click opens iTunes) is a free application that compiles the Internet streams from more than 150 public radio stations into a single list. You scroll through the list to your preferred station, then there is a screen with a play button and volume control. Over Wi-Fi, the station I picked came in clear with no interruptions. I can turn off the iPhone's screen and it'll keep playing. However, when I tried to launch Public Radio Tuner using a fairly strong EDGE connection, the application insisted that it wasn't connected to the Internet. I had to utilize another program that activated an Internet connection, then relaunch Public Radio Tuner, before it would work over EDGE. After that, it works as advertised, though American Public Media warns that some stations require a 3G or Wi-Fi connection to work properly.
It's a simple application, and does what it does well. It still needs some improvement. I would love to see a search tool implemented so you can bypass scrolling through the long list of radio stations; search by station name or by location would be great. The ability to bookmark your favorite stations would be an additional bonus, as well as tweaking the application to recognize a connection over EDGE without having to launch another application.