Microsoft today launched their web-based Xbox Music service. Xbox Music Pass subscription allows you to stream millions of songs on your Windows 8 and Windows RT tablet and PC, Windows Phone, Xbox 360, and the Web. You can even download your favorite songs so you can listen offline. It also features Smart DJ/Radio, just type in an artist and Smart DJ/Radio creates a playlist from similar artists. You can see everything in your playlist, and with unlimited skipping, skip to any song you want as many times as you want.
Your Xbox Music Pass collection automatically syncs across all your Xbox Music devices so you can easily access songs, albums, and playlists no matter where you are. All these were available only in Windows 8, Xbox and Windows Phone 8 apps, now they are accessible via music.xbox,com
Source: Xbox Music