Instead of blocking the distracting sites permanently, using iptables might work little better by restricting access by time of day or duration. [edit] I found

Instead of blocking the distracting sites permanently, using iptables might work little better by restricting access by time of day or duration. [edit] I found the following: http://news.ycombinator.com/item?id=192953 http://news.ycombinator.com/item?id=192953