Check out these resources that can be used to limit the amount of distractions you encounter online.
Readability takes any web page and converts it to a cleaner, book-like page to allow for easier reading.
Instapaper allows you to save articles or long passages of text in order to read them later, distraction-free.
Freedom is an app that locks you away from the internet for up to eight hours, unless you cheat and reboot.
Anti Social is an application that blocks social networking sites until you reboot your computer.