For the past couple of weeks, I’ve been using Last.fm to listen to streaming music online. I installed a small toolbar (really an extension for Firefox), and right from the Firefox browser, I can type in any artist I wish to hear, and the application finds that person wherever the music is playing on the Internet.
On the other hand, I also have the alternative to install the Scrobbler, the Last.fm application that can even import your libraries from WinAmp, Media Player or iTunes.
I prefer the toolbar. (^_^)
I have not yet found any music, any artist, any genre unreachable.