I had a lad with impulse control issues stay with me for a while. He had a Windows laptop for remote school work. After discovering inappropriate browsing, I tried various filtering methods, but ended up doing a full Ubuntu install and managing his host file via SSH.

I even had to unlist Google Docs (which his school used) because he found out that he could search for images in the word processor. When he needed to get a slideshow for homework, I ran a script which allowed access for 10 seconds so he could download and open locally.