Chat Rooms...

I would say chat rooms only because they can lead to the other problems of cyber-bullying, over-sharring, online predators, and so on...

I do think children should be educated and trusted, they also need their personal space (or at least have them think that) - there's solutions out there to generate reports on what they are doing on the computer, including the ability to capture every key stroke. I wouldn't go into a panic attack and start tormenting the child over what I find when spying on them (that would give me away), but the reports will tell me where I need to improve, and what to talk to them about.