inspired by dantheman’s previous finding here:
http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=133944
i found that the tick-mark-looking icon at the bottom of each post, to the left of the profile button, tells us who is online at any given time.
if it glows yellow, doper is online… if it’s dimmed out grey, user is on his way…
comments ? applause ?
I noticed that before. I think it’s cool.
Way cool!
I didn’t know that.
Thanks for the heads up on this.
I’m sorry, but that’s not what it means. To test it, look at some of your old posts, while you are online - they are all grey, while your new posts are yellow. See the connection?
You are thinking perhaps of another item which is often in that area of the screen, which the SDMB has disabled. I know this because my Board has both of them showing.
Well, not that the person’s online, but that they’re logged in - that’s my guess. 
Never mind, I was wrong. Just as I clicked “Submit”, I realized you were referring to something else on the page - the vBulletin symbol (which I did not recognize as a “tick-mark”). Yes, you are correct.
Whoa, a simulpost and I didn’t even realize it.
Anthracite, he doesn’t mean the one next to the date, he means the check mark right next to “profile” - which, if you hold your mouse over it, does say “X is online.” What it really means is that “X” is logged into the message board. Right now (since I haven’t refreshed), my check mark is highlighted (yellow), but yours isn’t.
Someone should mention it in the FAQ 
Paranoid people :looks over shoulder: enable the “invisible mode” in their user control panel, so that their online status doesn’t get displayed (and not to appear in the “who’s online” list, if it were enabled here).
aah… thanks femtosecond…