TechHive:

You’re well aware that you can purchase music directly over the Internet—from Apple’s iTunes Store, Amazon MP3, Google Music, and a host of other sites. And these are perfectly fine options if you want to own your music. But, for those who like to listen to—but not necessary collect—a vast library of music there’s an alternative: Music subscription services.Cough up $5 or $10 a month and you can listen to any of millions of tracks in a wide variety of genres, whenever and (within reason) wherever you want. I took a look at the major subscription services—Mog, Rdio, Rhapsody, Slacker, and Spotify—to see how they shake out and which might be the best fit for you.