Yes, someone did this:
http://jameshance.tumblr.com/post/61740 ... ts-work-in
What's interesting to me is that he's had to dip into Sesame Street as well as Fraggle Rock to find appropriate female muppets to embody Firefly's strong women. I was a huge muppet fan as a kid, but I think most girl muppet fans probably noticed the "girl problem". Most of the muppets were boys, except for Miss Piggy who was a raging b*tch. Janice was cool, and she was the with the band, but still.
This does remind me of how much I loved Fraggle Rock, even though I was a little order when it premiered, but still a kid. (11 when it first aired.)