I got my Skaven built last night. Nice little kit, but not much room for easy customisation without breaking our the scalpel & milliput, so they're built as per the instructions.
I was thinking about getting a couple of Skaven Assassins to use as extra gutter runners - the scale might be off though as the Blood Bowl guys are pretty hulking. Mind you, a small, nimble speedy rat might fit in well - like the little nippy buggers in Rugby.