Force members to upload an avatar...?

[dandan]

Is there a way to force members to upload an avatar or pick one during registration?

[Yaldaram]

Use this plugin: http://yaldaram.com/thread-645.html

This'll assign a random avatar to the new registrants.

[GunnerAIO]

I've been using Default Avatar by Aquilez for ages and it works great.. totally free and here on the mod section too:
http://mods.mybb.com/view/default-avatar

It has worked for me from MyBB 1.6.5 all the way to the recent 1.6.8 without one headache. The only thing is it's for only one default avatar.. if u want randoms like on wordpress.. then maybe you'll like the link from Yaldaram. It's a pretty cool feature but just sharing this just incase u only need like ur site logo to be used as an avatar on new profiles.