Radioshift is an online AM and FM radio player. It allows you to connect to thousands of radios online. When you first launch the application, there is a window that has basic information about the tool and some tips on how to make the most out of it. For example, it tells you whether you have the required codecs installed in your system. It seems that most radio stations use QuickTime or Real to stream, and you can install those players by simply clicking on the "install now" button on this screen. You can of course bypass this step and take your chances. I didn't install any players and was still able to open 90% of the radio stations that I tried to open.
There are radio stations from all over the world available in Radioshift. From the "Home" screen, you can either use the search field to search for a specific radio or find new ones by genre or look at the "Popular" radios and discover new ones. I personally liked the "World" mode, which shows you a satellite view of the world, and you can click on city names to view radios from those cities.
In terms of quality, all the radios that I listened to sounded very crisp. I would even say that they sounded better than on a real radio.
You can fully test this app before purchasing.