Random tip. If your camera somehow gets stuck at a weird angle, like looking straight down at your avatar's head or directly up from the floor, and Esc doesn't fix it....
... hit Shift-Esc a few times.
This key combo is designed to reset all of the CameraOffset settings — both visible and debug — at the same time. The reason you hit it multiple times is to make sure you don't have any other windows stealing focus.
It never hurts to then hit Ctrl-9, as well, just in case you also have a view angle thing going on, as well.