Perhaps it is easier to create a "lost and found" on nastyfans. It applies to each member individually. Then members have time to decide what should be done and where to send the refund. For each lost item a text area can be available for the member to enter instructions.
This does not clarify anonymous Bitcoin deposits. If suddenly 1000 BTC land in a nastyfans address I still do not know what to do. Maybe a general "lost and found" where we can use a poll to decide what to do.
I think that these, or something resembling/inspired by them are the only sane way to go. I wouldn't worry about the micro-donations, but as you said if 1000BTC lands in our laps then we should know (in general) our plan of action.