Pandora.com qualifies for yet another Web 2.0 application. Pandora started as a project to find the similarities in music and why we like certain music and why we don’t. The Pandora folks eventually made all their study of music into an amazingly customizable and accurate music service. To sign up is free although I recommend paying for the service if you use it a lot. Once you sign up, you start by building your own radio stations based on your favorite songs or artists. After you build your first station, Pandora starts to play songs related to the song or artist you started with when you built the radio station (which entails that you simply type the name of a musical artist or a song name and click Create).
As the songs play, if you tell Pandora whether you like the selection or not (via a click on a thumbs up or thumbs down icon), it will continue to more accurately pick music for you. You must see the short video below to see how it works, and better yet, give it a try to see why it is such an exciting and useful Web 2.0 application!