Ask HN: Active Common Lisp communities?

I've recently been exposed to CL. Hacked up a few trivial evolutionary computation problems, but I'm itching for something else; alas, I haven't any ideas of my own. I'd really like to contribute something to CL community (to help revive Lisp, etc.) but I'm not sure of where to start.

Does anyone know of any active communities where I could find some group-ish stuff to hack on?