I have found a new way to waste time. I recently started using Pandora.com. It is a site that streams "stations" at you that gives you some control over what you hear. They have several preloaded stations, but you can also create your station by entering the names of an artists or songs. As you song is played you can give it up a thumbs up or thumbs down. If you vote thumbs down, it bans the song form that station. If you vote thumbs p, it feeds you more songs like it. The idea is that, as you give more opinions, the station will learn your tastes and play more music that you like and less that you don't. The thumbs up and down only applies to the particular station you are listening to at the moment. That way if you have a blues station and jazz station, voting against a blues song on your jazz station won't keep it off your blues station.
It all works because they analyze each piece of music before they put it into their database. After analyzing it the tag each piece with attributes like "folk styling", "syncopated rhythms", "extensive vamping", "extensive use of the mandolin" and the like. The more attributes two songs have in common the more likely you will have a similar reaction to them both. It works pretty well, although it does tend to get stuck in a rut sometimes. Since it is mostly based on a what a piece sounds like rather than what it is, it can become difficult to build a station that plays only, say Irish traditional music. (I'm trying.) It seems that this system doesn't see a lot of difference between Irish music and bluegrass. However, if you thumbs down an artist twice, without giving them a thumbs up, it will ban them from the station forever. I've gotten rid of most of the obvious bluegrass players, but the system keeps throwing new, more obscure players at me.
Which leads me to a the next point, it is great at finding new things you never heard of, but wish you had. Case in point, I am a big fan of Sandy Denny, June Tabor, Maddy Prior and some of the other female singers from the British folk-rock scene and folk revival scene. Through Pandora, I've discovered Anne Briggs. She was enormously influential on all of the singers I like, but she only recorded about 30 songs over a few years and quit the music business at the age of 27. But in that amount of time she changed how all British female folk singers sang. She has since been eclipsed by Denny, Tabor and the rest.
Like I said, a great way to waste time.