Please, someone do In Nomine!
Or Deadlands.
I think a Firefly or Killjoy type space opera would be interesting, if you structured it in such a way that each "crew" had a storyteller (one or more) who ran stuff for other crews, and they in turn would run things for you. I love the themes of these shows, but they really do lend themselves to a more TT style slant, with downtime being social mixing etc.
I think someone already mentioned Dogs in the Vineyard, though I'm not sure how well that would translate to MU*.