KeepMeOut a web service that can help you to get over your addiction to certain websites (read Facebook, Twitter, Foursquare, MySpace).

How to use KeepMeOut
#1 Lets say you want to get rid of Facebook.
#2 Go to KeepMeOut
#3 Type Facebook in the text box below Warn me if I go to.
#4 Select the time frequency in the next text box say you want to stay away from a website for say 1 hour.
#5 In Advanced Settings you can set it for everyday or on weekends.
#6 Move the slider to set the time preference.
#7 Select Submit
#8 Save the created link as a Bookmark
#9 Use the newly created link to visit to keep yourself not addicted.