iRate is the first thing I will post about. As I have already said, the idea behind iRate is a wonderful idea. It has a database of free songs around the internet, and what you do is rate what you think of the songs it automatically downloads for you. It tries to get an idea of what music you like, and comparing your tastes with other people's tastes, tries to download things it thinks you might like.
iRate has a number of advantages over web pages and lists like this. The first, which I really appreciate, is no fiddling with "Save link as..." or dealing with archives. Instead, there is a menu item that simply says "Download more music", and it does just that, without even asking you what kind of music! Quite lovely.
The downside (to me) is that I found very little I liked. :(
Nonetheless, I heavily recommend trying out this program. It's a little rough around the edges but is definately something I am looking for.