Plenty, I guess. I found not one, but several sites online, which have directions for naming your book group! The most extensive set of instructions I came across was at eHow.com. Who knew it was such a big deal?
After you've considered eHow's suggested methods, you may want to do a search at the Reader's Circle site to see what clubs in your area have named themselves, or, you can simply put in a random zip code to search for unique names that you could borrow. Think punny or practical for your name choices, the sky's the limit.