I'm wordy. Here's a brief listing of fandoms by source, with umbrella series split out.

The Written/Drawn Word: +Anima, Book fandoms, Norse Mythology

English-language TV: Charmed, Doctor Who, Earth: Final Conflict, Sliders

Japanese TV: Digimon Tamers, Gokusen, Hana Yori Dango, Keitai Sousakan 7, Mei-chan no Shitsuji, RH +, Ultraman Nexus

Games: Fatal Frame (Project Zero/Zero) series, Final Fantasy series, Sid Meier's Alpha Centauri, Virtual Villagers series

Movies: Mulan, X-Men Movieverse

Other: Crossovers

Umbrella Series:
Kamen Rider: Kuuga
Power Rangers: MMPR, Zeo, Time Force, Ninja Storm, Dino Thunder
Super Sentai: Hurricanger, Abaranger, Dekaranger, Boukenger, Shinkenger, Gokaiger