I can't see any harm in adding a password to the adult/word filter options if that would make worried users (especially parents) feel better.

However, in my tests, these filters (even with a wide range of words added to the filter list) are not very effective and a large number of porn hits can still get through - for example those that simply have a girl's name.

Apart from that, the reality is that most kids have very little trouble getting round any security measures that parents put in place on the computer. For example, a friend of mine's little brother (12 years old) has his doting parents convinced that he's a little angel who only uses the net to research his school projects. But in reality, when he's not kicking butt in Quake 3 or Halflife, he's taking peeks at porn sites that his friends have sent him hacked passwords for. He also has no problems leaving the hard disk squeaky-clean with trace-removing software for when mum and dad come home. So if his parents placed security restrictions on the Web Browser or P2P software, he would have no trouble at all finding and downloading unrestricted alternatives. I have to add here that his elder sibling has excercised a teeny-weeny bit of influence in this pattern of behaviour though, to his credit, he ocasionally tries to instill a little bit of responsibility.

"But my little cherubin wouldn't do anything like that!", I hear parents cry. Well....you'd know better than I.