Hi Platonides,
Thanks for the list of robots at http://en.wikipedia.org/w/index.php?title=Special:ListUsers&group=bot
I just checked the list of all user groups at http://meta.wikimedia.org/wiki/User_groups . Are "registered users" available at the site above?
I maybe wrong, I couldn't find them in enwiki-latest-user_groups.sql.gz .
Thanks for your patience, Happy New Year