Well isn't this interesting!
You know I've got the hots for a Web 3.0 - provided its distinguished from Darkcoin the currency.
Keeping young people safe from the wild parts of the internet will get such global support from families and governments (someone raised a valid point on how you would keep kids off).
But, and on that note.
Drum roll, please.
SafetyNet (.SN)
Ta da!

SafetyNet could be made up of willing masternodes that have sophisticated child locks that can't be tampered with by the child.
Masternode would select SafteyNet=1. The node would only accept users who want to use SafetyNet and the safety tools that it provides.
But lets be honest, there are more important things to be concentrated on... Adoption/Open Sourcing/built-in PGP messages for anon delivery.