I notice that some people are still having problems with their avatars. Unfortunately any avatars that were stored on the forum were lost in the conversion to phpBB3. You MUST re-upload your avatar for it to show. This is done by going to your User Control Panel, selecting the profile tab and clicking Edit Avatar (on left).
I have changed the avatar settings slightly and you can now upload an avatar up to 130px X 130px with a maximum filesize of 19.5KB. If the filesize of an avatar you want to use is larger than 19.5KB, then use the Link Off-site option. You shouldn't need to use the avatar dimensions option as the size is normally found automatically.
Images in signatures were quite restrictive so they have been changed to a max of 120px in height with a max of 400px wide. The option to add or change a signature is found at the same place as avatars.