Rdio is now available to the public and is offering an unlimited free trial for 3 days when you create an account (no credit card required). It reminds me a lot of LaLa, which was recently acquired by Apple and shutdown (Oh how I miss you, Lala!). Rdio seems to have a decent catalog of music, and the streaming seems to perform wonderfully. So go crazy and listen to all the music you want free for 3 days!
After the free Rdio 3 day trial, you will have to upgrade to a paid plan. Rdio Web costs $5/month for unlimited web access and $9/month for the Rdio Unlimited plan which allows you to save your favorite music to your mobile device and listen offline. I don't think I'll be upgrading to a paid Rdio subscription any time soon, though. (Source: Lifehacker)