There are several groups and mailing lists which are either exclusively Archer/Reed or which have significant A/R content. Several of these groups also have fiction archives.
Archer/Reed is also well-represented on LiveJournal, with a community, two active role-playing games, and individual journals whose owners list archerreed among their interests.
Additions to this list are very welcome!
Live Journal Communities
Archerreed -- Anything Archer/Reed... fic, icons, art, discussion
Yahoo Groups & Lists
Reed's Archery Range -- Archer/Reed only... fiction, discussion, art
Reed's Armory -- Reed-centric fiction of all types, discussion
Archer's Enterprise -- All slash pairings, including plenty of A/R... fiction, discussion
EntSTSlash -- Slash Fic, announcements, discussion
Role-Playing Games on LiveJournal
TrekSoap -- Strong A/R storylines, multi-Trek community, plenty of angst!
Ent_Musing -- Strong A/R storylines, small community, new players welcome
Ent_Madness -- Meta community for Ent_Musing, a place for players and muses and readers to comment, show off new icons, make announcements