I've been on one other RP site that had a small section for these types of roleplays. I was surprised they worked, since they weren't all that chat-based and functioned much like many RP's here, except there were no CS's or approval processes - people just jumped on in.

I didn't spend very long there, but I imagine those RP's would require a lot of mutual trust between GM's and players to work properly. It all kind of amazed me, honestly.