Interactive content, go go go!
If you're unsure about the fanlisting concept, it's basically just that: a list of fans. There aren't any tough requirements or website elitism, it's open for anyone. It's also completely unofficial and kind of pointless. But fanlistings can be a lot of fun regardless, so don't hesitate to join. (Really, please don't! Nash needs an encyclopedic catalog of his fangirls like few others.)
Because no fanlisting about page would complete without it, I quote TFL:
"A fanlisting is simply an online listing of fans of a subject, such as a TV show, actor, or musician, that is created by an individual and open for fans from around the world to join."
If you're still confused and/or curious, there's a fairly nifty TFL 101 page.