Marvel Slash is the main community for Marvel slash fanfiction. The community is predominately m/m but welcomes other pairings.
From the Marvel Slash FAQ:
1. What's this about no X-characters?
- Until recently there was a ban on works involving any X-character, including Wolverine and Northstar. As of June 1, 2009, this ban was conditionally lifted. If you are predominately an X-fan, feel free to post your works but please do not flood the comm.
As of January 2012, the communty has more than 1000 members.
Affiliates and sister communities include: johnny_peter, stevelovestony, cap_ironman, marvel_100, xfiwts, raremarvelpairs, thor_slash, ontd_marvel, thorki, avengers_2k, avengers_tables.