I must say I'm glad that internet access wasn't so easy when my sons were below 15 or 16 years old!
I caught my one son looking at a graphic photo of lesbian lovers on the internet. He fled the room and denied it. I thought it was very funny but let him know that I didn't appreciate him lying. (that was before all the viruses and junk you can get on unsavory sites now)

As for being a snoopy parent, what we mostly did was threaten, and we lucked out with pretty good kids. As they've grown up they've told us a thing or two that they did when we thought they were being perfect, but nothing like sending nude pictures of themselves to their friends on facebook!!!!!!!!