Grooveshark/Spotify to Sharpen Student Focus

So my students have been listening to music long enough in class that they used to just start the songs on their iPods and not have to worry about it.  I let them listen to music as it actually helps most of them focus.  Now they often like going to YouTube.  The problem with that is that the kids have to find a new song, oh every three minutes and that is not productive. So I tell them they get one change a class.  So many use Spotify or my suggestion which is Grooveshark.  Both are free and let students find an artist and play any group of songs.  This will show my age, but when an album comes out it is the first place I go (everything is there) to see which songs I want to buy for my own playlist.  Try it out for you and your students.