I was wondering the same thing. I wasn't a member of the site when the first B&W challenge was done. I really would like to see another one offered up. I'm up for the challenge. :-)
There's also nothing stopping you taking pictures that aren't for the challenge...
What!!? You're joking, surely.
I second (or third, or fourth, or whatever it is) the B&W idea. I've only ever taken one shot that I really liked as a B&W, and it'd push me into some real learning territory.
Threre are a half-dozen or more really good photo contest sites that have DAILY black & white contests. Lack of opportunity should not be holding you back.