The Stargate should radiate waves like an external Babel fish, maybe?

It would have been such a good scene for "200" though... Jack standing in the middle of a clearing surrounded by natives saying "Excusez-moi?".. "Dammit Carter, I failed French and that was... that was a lot of years ago!"

But you do. And you not only want to write Martha/Jack, but you could write the Doctor being all "oh, for God's sake, don't you start!" about it all...