Some forums like Xenforo support Gravatar, so a user can choose to use their Gravatar rather than upload an avatar to the forum.
http://en.gravatar.com/
It would be great if Arrowchat could support this on forums like Xenforo so that where a user is using their Gravatar it also appears in Arrowchat (currently it doesn't and just shows the default 'no avatar' image).