I know that the users with a Ψ suffix are SE employees, and of course ♦ means it's a moderator.
But I'm seeing a handful of other greek characters too, like Φ - is that just other users being funny, or are there more "task force" teams à la CHAOS?
Here are some random examples:
You mean like this one and this one as well?
As those two are not part of any task force as far as I can tell, it means they renamed just for fun probably after the Ψ task force announcement. Can't tell for all cases though, but I'm pretty sure that we'll have blog post in case of any additional task forces.
Note that many change their names only here in Meta while leaving "normal" name in the main sites.
Your first guess is correct: this is just users being (attempting to be?) funny.
I assume it all started with this question, specifically Kevin's response, which says that there is no feature specifically in place to limit people adding certain symbols like psi (Ψ ) to their user name. He basically dares us to do so, I mean come on, what goes through your mind when you read this:
If you want to pretend to be one of the cool kids, whatever; it doesn't affect anything.
I actually thought about doing it myself, but then I realized it was kind of lame. Score 1 for laziness.
Sadly, of course, you still can't add a diamond to your user name. Michael Mrozek's insightful comment to the linked question spares the rest of us from having to try that for ourselves.
