Misc Notes
Do try and make your avatar sets recognisably yours; people use the avatars as a quick and easy way to see who's who, and if you have hundreds of unrelated avatars the purpose is lost. Keeping to a theme is good, eg I have random scenes with my character from the lego avatar generator edited in -- They're all different, but they're recognisably mine because of the common character.The Control Panel
The uploader should accept gif, jpg and png images; for some reason the image library doesn't seem to recognise some animated gifs as valid images. So far some animated gifs and all static ones work, I'm not sure what's different about the animated ones that don't...
Probably the only thing that isn't immediately blindingly obvious about the interface is the "toggle use" function -- avatars with "use: yes" will be included in the random choice, ones with "use: no" not -- this allows you to keep some avatars uploaded but only enable them for special occasions, eg christmas / easter / pirate themed variations.