https://www.beatsmusic.com
I downloaded the 7-day trial because there is some exclusive Nine Inch Nails EP that I wanted to hear, but I've rapidly come to love the service. For a subscription ($10/month) you can stream just about anything you can think of. I love being able to listen to anything whenever I want. This service is great.
Also, when you can't think of anything specific, they have this great music recommendation algorithm where you do a Mad Libs style sentence to describe your mood to get a custom made mix. It's really fun and there are lots of zany options. Here's an example:
Has anyone else tried this yet? I'm really excited about it.