Actually, that was one of our first thoughts for the RYO.  We were hoping that some existing book clubs might use the RYO to track their activities.  You can easily set up a challenge for a club and the organizer can add the books to his/her list as they get voted/decided upon and the rest of the club members can just copy the same books to their own lists. 

The only difference between a regular challenge and a club challenge is that everyone would read the same books at the same time rather than pick their own books for the theme.  The challenge page would have the same exact list of books for everyone in the club.  And of course the club could use the forum to host their discussions and set up polls for club members to vote for next month's book etc.

I love the idea but I don't have time to organize an "official WWEnd book club" but that's the beauty of the RYO.  Anyone can start a club and use the site tools to organize and attract remote participants.  You can even theme the club reads just like the regular challenges or organize separate ones for SF, Fantasy and Horror etc.  I'm sure there are lots of creative ways to do it.