There are several major archives where Archer/Reed fiction is archived. Some of these are indexed by pairing. In those cases, the links below are direct to the Archer/Reed index of the archive.
Fiction of all ratings is included in all of these archives; individual stories are all labeled with ratings and any warnings.
Additions to this list are very welcome!
Fanfiction Archives
Reed's Armory Collection on AO3 -- Active collection including Reed-centric fiction of all types
Reed's Armory Archive -- Reed-centric fiction of all types, indexed by pairing
Archer's Enterprise Fanfiction Archive -- Slash only archive, indexed by pairing
EntSTCommunity Warp 5 -- All types of ENT fic, no pairing index, but largest, most frequently updated ENT fic archive