On World Building

I am in the throes of one of my favorite parts of writing: world building. It's one of the things I love most about science fiction and fantasy writing (my second favorite thing is actually a subset of this: character building). My plate is full at the moment as I have two universes I'm building and playing in:

1. My alt-history, steampunk universe of Pimp My Airship. I am revisiting and expanding this universe because I have another short story I've been asked to write for an anthology ...