This is a variation of Rick Kennell's wish, #176. When the user's account page is displayed with a list of currently active sessions, sessions that are close to expiring could be highlighted in yellow or red, and when only minutes remain, they would blink. Clicking on a "+" sign or such would reset the access time for the session to the current time, without having to actually view it. The level for yellow could be less than 6 hours left, red could be less than an hour, and blinking for less than 15 minutes.

A less complicated, single-level variant could simply make them blink if there's less than an hour left.