Muziic is a new Facebook app that does exactly that. In contrast to many other music-related apps on Facebook, as soon as you install it, you'll be able to listen to music - and lots of it. Besides the featured songs, and the ability to search for albums, artists and songs (the actual music is pulled from YouTube), the most welcome part of the app is a list of online radio stations, organized by category, similar to the one found in iTunes.
All of this comes with very few restrictions; you can listen to complete songs, you can tune into radio stations for as long as you like, and you won't be bombarded by queries and obtrusive ads in the process. From the mouth of the app's creator, David J. Nelson:
"With Muziic, the goal was to create an application that actually gives Facebook users what they want in a music app. As someone who is not a big fan of most Facebook apps, I wanted to keep the experience clean, functional and user friendly. No incentivized garbage, forced friend invites, etc... Just a music app that delivers."
Muziic also enables you to easily create, save and share playlists, and comes with a quite useful Facebook tab that displays your listening habits, similar to the way it's done in Last.fm. On it, you can find user's playlists, recently played songs, favorite radio stations, top artists and top tracks.
My favorite part of the app is the fact that it doesn't go too far. If you want music quizzes, trivia or games, you'll have to go elsewhere. But if you're only interested in music, you'd do well to give Muziic a try.