Still working on the short story for Midian Unmade. Just a short story, mind you, but it has me looking up information on alopecia, Merlin, and herpetological symbolism in the Catholic church. (Spell-check recognizes one out of three of those terms.)
Research is a vital part of writing, even when you're writing about things that you're, well, completely making up.
A friend of mine once had the pleasure of watching a college librarian realize that the pile of a dozen books (everything the library had on the topic, plus some inter-library loans) that she was checking out were all, every single one, on the topic of human sacrifice. Admittedly, that was was academic research, and nothing to do with writing fiction, but even so: what's the weirdest piece of research you've ever done? The one that makes you wonder just how freaked out the NSA might be getting?