If you like discovering new music based on what you listen to and you haven't yet checked out Last.fm, you really should. It's been around for a few years now and received a "50 Best Websites of 2007" award from TIME magazine. There are many user-friendly features that differentiate it from the competitors and make it easy and fun to use, including widgets for your website, iPhone apps and music player integration, and even the possibility to start an online record label and make a little money if you have your own music to share!