The biggest problem I see with regards to the porn on the internet isn't its availability or controlling access. It's preventing people from *accidentally* accessing pornography, and this is something which is going to need cooperation on both sides.
For a start, typo-squatting should be discontinued on the part of the pornographers. It is a deceptive practice, and is one of the more common ways that a child can accidentally find themselves looking at pornography. Secondly, searching should only return porn results when you *actually search for pornography*. The easiest way to do this would be to give all porn sites a tag, and introduce a porn-search option, say, for example, porn.google.com. Normal search would exclude porn sites, and porn-search would *only* return porn sites. This way, both the web at large, *and* the porn is freely accessible and searchable, but it is no longer possible to accidentally stumble across a porn site. Finally, pornographers need to ensure that their advertising in only injected into appropriate channels, such that porn ads are not likely to appear on otherwise PG rated websites.
Controlling pornography *can* be done, if everyone does their part and the pornographers act responsibly.