I don’t mind admitting that I am so easily distracted by stuff on the Internet, that if I didn’t have a program like Freedom (Windows & Mac), I probably wouldn’t get much done at all. Freedom is a very simple utility that allows you to block your internet access for an amount of time in minutes. During this time, you won’t be able to access anything online, thus forcing you to do whatever it was that you were supposed to be doing (writing an essay, sending an invoice, tidying your room).
It costs $10, but there’s a trial version which allows you to try it five times for free. One of the unexpected benefits of getting this software has been that I now have a much better idea of which kind of job I am likely to procrastinate on or avoid, and on days when I know I have something like that to do, I switch Freedom on for 90 minutes as soon as I turn the computer on.