Great idea, I've had something like this in my head for awhile too.

My initial thoughts would be: -custom groups or more groups; what group is this person attached to. -change the "where" I met this person, for back entering people. Everyone I'm entering the first time, right now, is off. -some ability to record meeting that person again? You probably don't want to turn this into a CRM, but having a history of when and where you met someone would be helpful.