Flag abusive users
I'm not sure if there is a post about this already. I searched my title text and the first two pages returned nothing useful, so here goes:
I have just come a crossed a user with (imo) a questionably inappropriate username and gravatar match-up ( http://stackoverflow.com/users/23875/dropped-on-japan ). I was wondering what (if any) was the course of action when these are found? Although the particular case here does not overly offend me, I can see how it is offensive to others. I have also seen in the past racial and profanity in gravatars and have reported those directly to mods via the chat system (should that be the course of action here as well?)
I guess what I am really looking for is a "flag user" button or option on the main site (which I cannot find).
tl;dr - I'm curious to know how to report inappropriate usernames and/or gravatars.