I like the idea of Martha/Julian Bashir! Next Multiverse?

Multiverse is good for so many things *g*.

Also, you forgot Martha/Shakespeare, which is still an option since Ten has to visit Elizabethan England again. Unless she stands firm on her principles (that him being married and having bad breath thing...)

If I started considering characters who only turn up in one episode, I'd have ended up with Martha/Charles Dickens *g*. Which, actually, is not the worst idea I've ever had ...