After a bit of getting used to it, I find I like what Last.fm offers, and the widgets aren't half bad either. Clicking directly on the track will only give you a 30 second preview. The only way to hear complete tracks is by clicking the big "Play" button, which then plays songs randomly. A way to go around copyright issues I guess.
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However, b2evolution was allergic to the code as it was, and I don't have right now the time to convert it all. So, for the time being I'm only placing a stripped-down version of my Last.fm playlist widget. It doesn't look 100% correct in IE7--the Play button is not centered--but it looks perfect on Firefox and Opera.
Their downloadable AudioScrobblerapp is similar to Pandora: generating a streaming "radio station" tailored to your music tastes. Pandora's interface is far simpler, but I must admit I like using Last.fm's app quite a bit. The AudioScrobbler link I posted here is for the BETA version 1.4, which gives far more control than the current version on what you want it to run. For instance, when you open the app, it also activates LastFMHelper.exe, which doesn't help you very much if you don't have an iPod (and it stays active even when you turn off AudioScrobbler). You can tell the app NOT to open it next time. In version 1.3 (the current stable) you can't do that, only terminate the helper app manually and then renaming it to something else so it doesn't run next time (Windows will pop up a nag screen telling you it can't find the file each time you open AS though).