I think we can get some inspiration from the forum that I moderate, Inside Pulse. Basically, what I envisioned happening here has happened there quite successfully. Check out some of the neat writing experiments that we've started up there, including the "Writing with Restrictions" series, the MSA game, Syllables, Complete the Sentence, The Rhyme Game, among others. I am "Chaos" there, so sign up and post here: http://www.insidepulse.com/ubbthreads/postlist.php?Cat=&Board=creative
This might help us to get some inspiration going for this community here.