RanmaMUCK
Center for people interested in online roleplaying and general anime/manga fandom.

Jyusenkyo's Densetsu
Rules, character adoption, member list with profiles, stories, and links.

Sakura's Ranma RPG
Play by e-mail. List and information on characters and membership information.

Neo Ranma 1/2 RPG
Rules, character adoptions, story lines, links, and existing character profiles.

Cat Cafe RPG
Play-By-E-Mail. Application, rules, cast list, and fan fiction.

Ranma 1/2 RPG
Play by e-mail. Choose an existing or original character. Membership information, rules, pictures, and story summary.

Yahoo! Groups: The Tendo's Dojo
Role playing via a mailing list.