I have seen it before. Looked into my bookmarks, couldn't find it. However google gave me a few hits: http://serghei.net/humor/swf/avatars.swf, http://www.dookyweb.com/avatars.swf redirecting to http://www.buscarmessenger.com/avatars.swf

buscarmessenger.com may be able to inform you on the origin of this avatar creator as they have it advertised in one of their html page: http://www.buscarmessenger.com/avatars.html

In the avatar creator category, a very nice version is "drole de tete" (title in French, website in English): http://www.droledetete.com/