There are three types of private account info I've been considering:
* unexposed in the user interface/hidden/API-only user preferences;
* user session information; and
* per-action CheckUser-related information that's temporarily stored.
What I'd like to see is a single portal (e.g., Special:AccountInfo) that
combines and enhances the functionalities of these two extensions:
This portal would be a straightforward dashboard that allows users to see
and manage the private information associated with their account. Advanced
user preferences would be toggle-able (similar to chrome://config or
whatever), active sessions could be inspected or terminated, etc.
Perhaps this special page would require successfully entering the user's
current account password to avoid a bad actor jumping on a victim's
computer or other similar types of nefariousness.