Using the Google Chrome extension Chrome Nanny, you can limit yourself from going to some sites on pre determined times or limit the time you spend on some sites. You can, for example , block yourself from going to a site between 9AM-5PM or limit yourself to 60 minutes in a site within a day (or even both).
What's new in version 0.990
ReleaseJuly 25, 2011
Date AddedJuly 24, 2011
Operating SystemsWindows 2003, Windows 2000, Windows Vista, Windows, Windows 7, Windows XP