I know this is a weird suggestion, but I'd like to see some album for you to put all avatars you like to use, so you can switch them easily depending on your mood of the day just something interesting to think about.
I think this is a small feature / tweak, so I put it here.
My idea is, it's like the msn, when you get a new display picture, it saves your old one the in selection, so XenForo could have something like this. I made a picture of how it could look. (Picture is rubbish, paint.)
You click "See Your Avatar Gallery" and a box of any avatars you uploaded will pop-up in a box, so you can select any old avatars you may have used.
That's about it, if you like this suggestion / hate it / or got something to say to improve it. Reply.
I like the idea as well, but it was requested previously and the response as I recall was this feature would not be supported, but could be created as an add-on. Sorry, I can't locate the link to the thread.