How do you stop reading the internet when you need to work?
coliveira: This is a really difficult problem, specially for developers. A solution I use is: 
a) decide the times you want to access the web. In my case is early in the morning, and after lunch.
b) If this is difficult to stick to, maintain a timer of how much time you spent away from the web. Try to maximize this quantity as your secret personal task during the day. This works really well for me.