I had an awesome idea earlier as I was watching the episode of ST:TNG in season 6 where Picard has a romantic relationship with the head of astrophysics. The idea is this: Captain Jack Harkness, for some reason, gets in the TARDIS with The Doctor and they accidentally get sucked into another universe - the Star Trek universe. Something else happens to keep them from being able to go back through right away, maybe it takes them several weeks to figure out how to get back. Anyway, plenty of time for Captain Harkness to seduce Captain Picard. As we've seen with Ianto, Jack can turn the straightest men into bisexuals, so it could work. :-)
Someone else can have the idea if they want it. I barely have time for my own writing, much less for fanfic.