What is the bar on your signature space? Some kind of internet radio?
Well, it is that, but it's also ties into your music player and charts your most-played individual tracks and artists. That's what I use it for. And there's some more community-oriented stuff it does, too, like recommendations, journals, reviews, and so on.
More at WikipediaAnd you can click on my sig and check out my profile there, if you want.