I might as well put this into writing myself.
Avatars
1. Maximum size - 80x80 pixels
2. Absolutely no animated images
3. No offensive images
Signatures
1. Maximum image size - 500x80 pixels
2. Maximum text length - four 'normal size' lines without an image or two lines with an image
3. Absolutely no animated images
4. No offensive images
We will give everyone the rest of the week to comply. Admins will reserve the right to remove avatars and signatures of offending members without warning by July 15, 2007.
Thank you.