Filtering the internet is just a stupid idea. It is far to costly (if not done automatically) and will inevitably filter the wrong things. A simple anti-child pornography site to raise awareness and get rid of those sick bastards would most likely end up triggering key words and get banned. That can easily be overcome though through various methods however.
Elsewhere, the widespread availability of strong encrytption would prevent governments from monitoring the real serious people. They would only be able to get info from the losers, nutcases, crackpots, and foolish terrorist wannabes who don't have the brains to protect themselves. These people are no real threat anyways. The real threat comes from organized, intelligent people who are serious about killing us. They will not make silly mistakes like that.
I remember years ago one fellow always posting news bulletins that were encrypted. He also posted the keys to access them - every key was carefully crafted with keywords that would trigger NSA alerts. e.g. "I sent the guns so that you can assassinate the president of the attack dog kennel. Bomb him with c4 if missiles or anti-tank rockets explode the white house or ak-47's eat pickled plutonium covered in semtex sauce."
Other general access sites like racist sites, etc., although evil, should not be banned. Whether or not I agree is not the issue. They just need to be monitored. Not the rest of us. However, that monitoring should be carried out wherever they are physically located. If the problem spills over, foreign governments should simply make their concerns know to the domestic government for that case.
Politics sucks.