Summer Writing Challenges?

So, I have a seminar paper to finish, but I'd really like to have something creative to do on breaks from that.  Do any of you know of any good summer writing challenges/prompts/comms/etc. going on now or soonish?  Nothing quite big bang-ish, but a little meatier than drabbles.  It's been ages since I've written something that wasn't a book review or response paper or research, and the right sight of my brain doesn't want the left side to have all the fun.  Thanks!