Although SO already has Markdown and HTML, it would also be nice if BBCodes would also be supported. They are a de-facto standard on many internet forums and it would help new users if they could use the syntax they are used to. Even I still catch myself writing bbcodes very often and have to re-edit my posts to replace them with Markdown. And I've been using SO nearly every day for more than a year.
Added: Seems that people totally misunderstood me. I didn't mean to add more formatting possibilities. I meant to add the possibility to use the same formatting possibilities already there, but with bbcode syntax. So you can use [b] and [i] and [code] and [url].
Added 2: Wow, 11 downvotes and only one upvote. O_O Certainly not what I expected. With BBCode being so ubiquitous, I thought people would like the proposal.
I know that Jeff went through a bunch of markup languages and disliked BBCode - but that's just Jeff. As he has often said himself - the people run SO, so the people are the ones who get the most say. So I just spoke my mind.
Well, this certainly proves that people around here don't like BBCode. So be it.