Just what the title says. In the user-bar (upper right, in english) the avatar icon, which currently links to [username]/activity, should have a dropdown menu, similar to all the other items in the user-bar.
Some targets available from the menu should be:
As (if) it becomes available, I would add:
Such a menu is a fairly standard feature of websites today, and would be consistent with the styling of the user-bar. Also, it is weird to make me go to another page to logout.