Here is a refined version of the idea taking your feedback into account...
TheScreenplayExperiment.com remains an experiment in collaborative creativity. At the lowest level, we have a discussion board for tossing around ideas. Above this, we have a collection of wiki's for writing rough drafts. Registered users can contribute to these wiki's. At first, we maintain ulitmiate control, but, the plan is, we invite users to become the moderators for each wiki based on their participation. Finally, once the rough drafts begin looking good, we have the entire community of registered users vote on which one they like best. At this point, the moderators of that draft can clean it up, and then we're done.
Following Michael's points from earlier, the idea has low risks, guarenteed small returns, and large potential upside. For example, browsing the site has the immediate return of reading the current state of the movie ideas. People are interested in movie concepts. And it's a good 10 minute distraction to check in every few days to see how the plots are unfolding. Are they stupid? Are they cool? Are they crafting a wicked twist ending? At the next level, participating in the ideation, the return is receiving recognition for your creativity. It feels great to have an important plot point or character be added on the basis ofyour recognition. At the highest level, is being a moderator. The benefits here are clear, you are in control of a creative community. Very ego-gratifying. The potential large upside is the treatment eventually getting turned into a movie. This is not a financial upside. It's a cool-factor upside. You were a part of Hollywood history. You can go to a movie, and know that you had a part in making it. In fact, you can go to a movie, and point to scenes that you yourself actually constructed. Great, fun, and exciting.
The key that brings this together, at least from a publicity and community standpoint, is this guarentee that the site owners will sell the treatment for exactly $1. In fact, we should have part of the registration process be clicking on an agreement that basically says "I am participating only on the understanding that the resulting idea can only be solds for no more than $1." There's the hook. It transforms this into a creative, community venture. The common movie-goer fighting against the excesses and mediocrity of the studio system. We think your movies suck, and we can do better!