I'm still flabbergasted when a company lets me index their entire AD tree as a random (or, holy crap, anonymous) user. Very nice of them, but still.

It's also often the only way to get information that doesn't exist in an Intranet page, like, literally what teams are there in IT, where are their offices, who's somebody's manager, and of course, what distribution lists am I not on that some other user is on that's causing one of us to have issues accessing some internal company portal.