As Museums are for things to Gaze at...
...Words are for Libraries
Simply banning Images from unapproved sites satisfies both "unfettered access to information" and 100% bans the most immediately, obviously obscene
Most people could read James Joyce's Ulysses (1922) straight through and not notice anything of an ordinarily vulgariform.
There will be those who conscioudly design obscene letters with containing certain terms that would lure in children looking for normal, child-things.
Material that seems to satisfy those conditions should be put in a separate TLD, unavailable to children.
With this post, I do commend the Supreme Court of the United States to withdraw their recent (2003) decision concerning these matters, and for them to commend to the Congress of the United States to enact appropriate internet legislation