Dealing with "teens" on your site?

[MPDev]

I'm curious how people handle teenagers registering on their site. Does anyone have special conditions setup for teens (say under 16) that limit their posting/reading capabilities?

I'm thinking of establishing a teen usergroup, but not entirely sure how to automatically move those with birthdates in the < 17 range into their own. I've added Andreas mod for the no registrations under 18, but am considering adding some forums for teens to give them a reason to use their real age.