If you've read Deathly Hallows, here is a super interview with JK Rowling. Tiny excerpt:
Question: What would your patronus be?
JK's answer: I'd like an otter, like Hermione, but I've got a feeling it might be a large dog.
I'd like a panda, because they make me feel warm and fuzzy, they are in essence Chinese, though many transplanted, like me, and the efforts of many to save pandas (among other endangered species) give me hope of our humanity.
What about you?