I check my e-mails too much. And from time to time I find a webpage that I keep checking too much (a forum thread and the likes).
What tools can I use to restrict my access to these pages?
(I use Windows XP with Google Chrome.)
There are extensions in Chrome for blocking websites to increase your productivity. You might also want to try the desktop or Chrome version of RescueTime. I haven't use the Chrome version, but the desktop version does have a "Get Focused" feature to help you stay on track.