I've always kind of been interested in the idea of having an RP based off of a "what if" scenario centered around "Living Witness", the episode of Voyager where the doctor is activated in the future and discovers that an alien species remembers Voyager as a warship full of ruthless war criminals who would do anything to get back home. Basically, this RP would take place in a universe where said aliens got it right and Voyager was exactly how they described it. Not quite Mirror Universe, but a similar feel.