No Entry
by Chris MacDonald
I love this one, for some reason. It’s on an otherwise inviting door in a university hallway.
Simple. Succinct. Mysterious. What’s not to love?
Normative Signs: The Poetry of "Ought"
In which the author finds beauty in how people tell other people what to do.
Normative Signs: The Poetry of "Ought" 
I’ll tell you: Because it’s defined by what it isn’t.
There’s one of these in my office building, and someone wrote in tiny letters under it, “Exit?”
(Obviously, labeling it that would only lead to more confusion, but you take my point.)