X-Men

Genesis-X RPG
[Messageboards] Based in the future just after a war involving humans and mutants. [Game no longer active. Archived posts may be of interest.]
http://www.geocities.com/oldrpg/frame.html

The Real X-Men
[Messageboards] Roleplay a member of the X-Men. Rules and available characters. Game played in a Yahoo! group.
http://therealx-men.tripod.com/main.htm

Themed
[Messsageboards] Based on X-Men comics. Available character list, biographies and rules.
http://themed.proboards19.com/index.cgi

The Uncanny X-Men RPG
[Messageboards] Freeform roleplaying setting. Rules, how to join, available characters and staff list.
http://baku-panda.org/ux/index.php

X-Factor
[Messageboards] Set just after "X-Men Reload" takes place. Canon characters only. Available character list, rules and application template.
http://p210.ezboard.com/bxaviersdream

X-Men: Dark Evolutions
[Messageboards] Based on core Marvel universe set in Salem Center, New York. Players can play Marvel and original characters.
http://p200.ezboard.com/bxmendarkevolutionsrpg

X-Men: The Gifted
[Messageboards] Players roleplay characters enrolled at Professor Xavier's School for the Gifted. Canon characters are not permitted to be played.
http://members.lycos.co.uk/rpgxmen/xmenrpg/

The X-RP
[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.
http://www.fengs-shui.com/xrp/xmen.html