• How people arrange their financial accounts with their significant other.
• What kind of car people drive and why they like it or hate it.
• What personality type people are in some system, and whether that system rocks/sucks/is scientifically valid/is total bullshit.
• [Added 9/22] What kind of houseware people own, or wish they owned, or have inherited, or how little they care about any of this.

This list to be added to the next time I end up in one of these.