Pandora Radio
Pandora Radio is a free internet streaming radio service that allows you to create personalized stations. The stations select music based on similarity using data from The Music Genome Project. You tell it something you like and it will find other songs you probably like. As you listen, you can tell it what you like and dislike so it gets a better idea of your preferences.
I’ve been using Pandora on and off for a few years and it works pretty well. I’ve discovered some great bands I never knew I liked or even heard of. It’s a great way to discover new music. Of course it also plays a lot of your favorites, too.
You can even further customize your stations by mixing them together or manually adding bands for more variety.
The free version has some short ads and a few limits on usage, but it isn’t too bad. I’m actually thinking of getting the paid version that removes the ads and limits, as well as gives higher quality and a desktop application. Right now it’s only $36/year.