What does work in regards to parental content filtering? I can't think of anything that a reasonably computer-savvy kid couldn't get around. Re: .xxx, I didn't

What does work in regards to parental content filtering? I can't think of anything that a reasonably computer-savvy kid couldn't get around. Re: .xxx, I didn't mean it was perfect, or even an effective solution, just that it had some value and meaning compared to .co, which has none (IMO).