When a meeting, or part thereof, is held under the Chatham House Rule, participants are free to use the information received, but neither the identity nor the affiliation of the speaker(s), nor that of any other participant, may be revealed.

Could be useful for fandom things (online conventions?)-- if someone is private and doesn't want their stuff added to, like, fanlore with their name attached to it, then this rule could be a good starting point to make people more comfortable talking in a group setting.