I was thinking (until my uber crash-ahhnialating anything digital on both the PC's, including my work for FA) you could go the other way, try a 24 style approach for a campaign. The last day in Cappela springs to mind.
Sorry, off on a tangent there. You could try make it a sort of mini Fred academy. Have a very, very general plot (pilot in outer rim, post Cappela) and anyone who wants, adds a mission to the story, one after another. So one week you have you saving the universe from 50 Sathanai (from one of our 'newer' members), and the next a simple, yet fun, escort mission.
Could work, but like Aldo said would be hard to organise, and of course like any other 'user-made' project any deadlines shall be overrun. By at least 2 years by my reckoning...not that I'm pointing fingers (Hell, were all to blame).