The "last seen" information is on every user profile, and I would argue that in some cases it compromises user privacy and voting anonymity (though others clearly disagree). I think this is particularly an issue on smaller sites in the SE network.
Why does the "last seen" time need to be so precise? I'm fine with "last seen 2 hours ago", but how is it useful to know someone was "last seen 2 minutes ago"? It is useful sometimes to know if a user has been on the site in the past day, or perhaps the past hour, but I cannot think of a reason why anyone needs to know another user has been on the site in the past 2 minutes.
Furthermore, the last seen time is inaccurately precise. The time is not updated instantaneously, meaning that when it says "last seen 2 minutes ago" someone may have been active more or less recently. Which means that the site is displaying incorrect information some, maybe most, of the time.
I therefore propose that "last seen x minutes ago" be replaced with "last seen <1 hour ago" or similar. I feel this would provide just as much useful information, while providing better anonymity of site use and voting, and also more accurately represent user activity.