I think this is a great idea, but I have a question:

If we're going along, writing a scene/post, blah blah, and we're getting ready to throw an npc into it, are we supposed to just do so, and if someone wants to play that npc, they'll suddenly pop up in the thread? Or do we post to the ooc comm and announce that an npc is needed?

None of the above?

I'm e-mailing you now about #1!