"Row, Row, Row Your Boat" by Denise is a "crossover of sorts with Deadliest Catch" where they are all fishermen or members of the Coastguard. This isn't a community, but still pretty awesome and becomes Sam/Jack:
http://sg1-heliopolis.com/archive/viewstory.php?sid=4527&chapter=1

And it's sequel "Motley Crew":
http://sg1-heliopolis.com/archive/viewstory.php?sid=4528&chapter=1

ALC Punk's "Caper" is set in the 40's and is a parody of the old film Noir detective stories (that I only know of thanks to the parodies of Bill Nye the Science guy;). It features O'Neill as the hard boiled detective, Sam as the alluring client with a mysterious past and various other SGC characters:
http://lyssie.the-family-archives.com/ana/caper.htm