The USS Atlantis is a Trek-based collective writing effort (formerly known as RPG or SIM). First begun in 1998, it was a spin-off of the now-defunct USS Banshee, NCC-2020-B.
The USS Atlantis has gone through many periods of varying activity levels, included or collaborated with other groups, but has always been in continuous operation. The basis of the USS Atlantis' mentality is that one should write to the NOVEL, rather than focusing exclusively on one particular character (regardless of whether what was submitted had any bearing on the main plot points). Further, "mimimum posting rules" and such are not used as members often have periods of higher and lower creativity, inclusion in a particular plot point, and real-world interferences.
Recently, the USS Atlantis altered its direction with a change to a post-Enterprise time period and the "new" warp-7 ship, the Atlantis NX-12.
The characters on the USS Atlantis have shifted widely. Some characters have, through the group's history, had many writers. The longest-running characters at the conclusion of the post-Nemesis era were Jacob Ryder (though deceased near the end), Alexis Ryder (adopted daughter), Harry Wolf, Finn John (a civilian journalist), and father-son Admirals Kennedy and Fitzgerald August (the bad guys, in a sense).