I’d like to point my readers to Pandora, a streaming music service which lets you define multiple channels for the different types of music that you like. You start each channel with a seed, which is a song or artist that you like. The service chooses songs similar to this and you then mark them as thumbs up or thumbs down, thus refining the channel more towards your musical taste. It is Flash and browser based, no downloads necessary. Sign up is easy, and the service is free, though add supported. Highly recommended!