So, I was looking for minis and I randomly came across a set of Dr. Who themed ones. Figure some of you would be interested.
There's also these which were used I think for a miniatures skirmish game.
Not overly fond of the sculpts but it's nice to know that kind of stuff is out there.
There's also a number of modern civilian minis from various lines that could be converted fairly easily.
ETA:Also, the link Caineach put up... the same company also does some nice not-Firefly figures.