I just posted an answer for What criteria determine whether a Stack Exchange site should carry ads? question and noticed the Adzerk's About Stack Exchange excerpt on the right says "Stack Overflow, a forum..."
Here is the screenshot of it:
I have seen many posts that gets immediately edited whenever someone writes Stack Overflow is a "forum". I have also read the popular post Is Stack Overflow a forum? (including comments). I think it would be great if someone from SE could make a request to change the "forum" word.
P.S.
The official Stack Overflow tour page says: (emphasis mine)
Stack Overflow is a question and answer site for professional and enthusiast programmers.
and,
This site is all about getting answers. It's not a discussion forum. There's no chit-chat.