I'm not overly conservative, I don't think I'm overly porn-protective or predator-hysteric or whatever, heck, I might've leeched a naked lady or two myself as a teen (at 2400 baud!) and don't think I became a Fox newsesque freak. That said, I don't think it's a good idea to let a seven year old roam the Internet freely (I cringe just thinking about my niblings reddit.com/r/wtf , and I know there's much much worse online). I think it's probably a very bad idea to let the government/an ISP protect the said seven year old, but I don't think s/he should be left alone on the Internet. I'm not even sure what are reasonable cutoff parameters by which to decide when and how give your child more freedom as they approach online adulthood.
What should a sensible, liberal and caring parent do to protect a child online over various ages? I'm interested in answers protecting toddlers to late teenagers, in answers targeting the whole range of tech-savvy to tech-clueless parents, including 'tech clueless but with a tech savvy friend/sibling who'll help set things up' and finally I'd definitely appreciate pointers to good, techie-oriented, not tawdry and not disgustingly commercialised information/opinion sources.