The popular UK music service Spotify now is available to folks in the U.S.
Even if you haven't received and invitation to the service yet, I have a workaround for you to access it.
Just head over to Klout.com and sign up with either your Twitter or Facebook account. Once you sign up, click on Perks near the top of the screen. You'll see an option to sign up for Spotify at the top of the list.
Click on the Spotify offer to get your invite code--I blacked it out here. Then set up your Spotify account.
After you create your account, just follow the site to download Spotify for the OS of your choice. If you like, use the link that Klout gives you to give access to your friends.