One interesting feature we already have is Location which is configurable by users and visible in the user card (when you click on an avatar).
I can see that in some very specific forums (for example internal company Discourse) it would be very powerful to “automatically” set location. In those case automatically making TZ visible in the card may also be interesting.
This stuff is a lot more feasible now that we have IP → locations thanks to @nbianca’s work.