A fanlisting is a place for all fans of a particular show, movie, actor/actress, singer, etc. to come together and build the biggest listing of people from all around the world who are fans of that subject.
(from TheFanlistings.org)

This particular fanlisting is for fans of Kawada Mami's song Akai Namida that was used as an insert song in the Sakugan no Shana anime movie. If you're one of them, feel free to join!