What determines when a user was "seen"?
128430
Account "last activity time" is not always updated
141755
Ignored users still appear in the 'other rooms you're in' message preview
48736
How can I find out if the current user is in a specific group?
50060
Obtaining the likelihood of an individual observation
140353
Why is my account appearing on SO top users?
118936
What happens when an invisible creature is detected?
67843
Determine logged-in status of users
77953
In activity monitor what time frame is the data sent / received data from?
147728
Follow activity of certain users
59271
How can I figure out who has visited my profile?
68304
Visited links should be more visible
7959
Timestamp on question is later than Profile's Seen, must be some time traveller or ninja
10365
How do I control who can see my Friends List?
115642
Notification that ‘someone might be watching what you browse’
126742
Can moderators see each user's Votes tab?
156269
Show if a user is online, idle, or offline on their account page?
119727
Notify users when they are mentioned (on meta)