The X-RP
fengs-shui.com
[Messageboards] Freeform roleplaying inspired by the Uncanny X-Men comic series. All characters are original, rather than canon, and are assigned a power by GMs on acceptance. Includes rules, character biographies and how to apply.
X-Factor
p210.ezboard.com
[Messageboards] Set just after "X-Men Reload" takes place. Canon characters only. Available character list, rules and application template.
X-Men: The Gifted
members.lycos.co.uk
[Messageboards] Players roleplay characters enrolled at Professor Xavier's School for the Gifted. Canon characters are not permitted to be played.
The Real X-Men
therealx-men.tripod.com
[Messageboards] Roleplay a member of the X-Men. Rules and available characters. Game played in a Yahoo! group.
Supernating Superdudes
superdudes.net
Players create a superhero based on themselves, create a trading card and then participate in various competitions against other players.
Young Just Us Teen Titans.
s4.invisionfree.com
[Messageboards] Superhero roleplaying based on DC comic characters. Rules, forums, available and taken hero listings.
Genesis-X RPG
geocities.com
[Messageboards] Based in the future just after a war involving humans and mutants. [Game no longer active. Archived posts may be of interest.]
X-Men: Dark Evolutions
p200.ezboard.com
[Messageboards] Based on core Marvel universe set in Salem Center, New York. Players can play Marvel and original characters.
The Uncanny X-Men RPG
baku-panda.org
[Messageboards] Freeform roleplaying setting. Rules, how to join, available characters and staff list.
Themed
themed.proboards19.com
[Messsageboards] Based on X-Men comics. Available character list, biographies and rules.