A fanlisting is a web clique that lists fans of a particular subject that is created by an individual and open for fans from around the world to join. Unlike most web cliques, a person does not need a web site in order to join. There are no costs, and the only requirements to join a fanlisting are your name and country. Fans from around the world submit their information to their approved fanlisting and they are then listed to show their love for the subject.
In this case, the subject is the relationship between Clark Kent/Kal-El of Krypton (Superman) and Diana of Themyscira (Wonder Woman). If you are a fan of this relationship, then by all means, join!