If you're a big fan of Last.fm-style, then you might like Finetune Desktop because it works in a similar way in helping you discover the kind of music you might like.
However, this is a far more sophisticated affair because it's based on Adobe Air. There's very little to it except to select those artists that you're interested in and Finetune Desktop will guide you to the nearest equivalents or those with similar styles. In addition, you can filter music according to style and genre. The advantage of using AIR is that adobe have moved their product away from the restrictions of Internet Explorer which it was formerly locked to. By using AIR, Adobe have also made this a truly cross platform application. Using AIR also has other advantages - AIR can capture music preferences stored on your desktop such as those of your iTunes library and then feed it into Finetune’s recommendation engine. You are then offered well-matched songs based on artists, genre, and playlists that you already listen to. In addition to helping you find artists that you might like, Finetune Desktop can also stream Mp3's directly from the net.
This is an interesting innovation from Adobe that could prove a worthy competitor to Last.fm if it gathers a bigger following.