My forum has an under 18 group. I have to go into the persons profile, and manually assign then to that group - this is a waste of my time. If a person is under 18, I should have the ability to assign them to an Under 18 group.
And its not just for people under 18. This could be for any type of information the person enters when they register - age, race, sex, religion,,,,,,.
Lets say I'am running a forum on religion. When a person registers, and they check the Jewish box, they would be assigned to the Jewish group, which would have spcial access to the Jewish forum section.