Doctor Why - doctorwhy
This one's pretty much straight-up Dr. Who satire.
Torchwood Babiez - tw_babiez
Think Muppet Babies with a sci-fi twist.
Darths and Droids - darthsanddroids
If the Star Wars saga only existed as an RPG campaign. (Yeah, I know it's not BBC, but it's damn funny.)
What are some of your favorites?