I think it would be a nice features for moderators to be able to set a topic as "PG" we often have topics and jokes threads that are only really suitable for an adult audience but I don't want to remove these outright. i.e. guests have to confirm they are over a certain age before viewing. I know we can restrict registration but I think that this denies people access to the majority of content that is perfectly suitable for all ages.

This could be done with Topic Multi-moderation within the Admin CP.