Carousel: Open Ended Collaborative Fiction : Carousel is an open-ended, sequential collaborative story created by the community. Started January 15th 2009, Carousel is open for public registration. Have a look at the posting parameters and dive right in!
Ides: Rouse a Frantic Muse : Ides is a public project not dissimilar to NaNoWriMo on a somewhat smaller scale. There is no run of Ides running right now, but check back at a later time as we will open one at some point in the next few months.