I don't use Facebook, but if you ever post information about the design (under a lock, presumably), I'd be up for kibbitzing at a theoretical level.

The report logs of sites already dealing with abuse problems could be quite informative, if you could figure out how to get access. Failing that, you can sometimes glean information from reading their abuse policies; if they're specific enough, you can start down the path of "why would that be a problem?" and maybe reason it out. Just guessing, but policies are at least generally public, so it's easy to look.