It's very useful for me!

Take control of your browsing time with Browser Timer

It is really easy to lose track of time when you are browsing the Web. I created a program called Browser Timer that will close all your browser windows after a user-specified amount of time. Browser Timer works with Windows XP or Vista and Firefox, Internet Explorer 6 or 7, and Opera. Browser Timer is a stand-alone executable written using AutoHotKey. See the screenshots below:

Download Link: Browser Timer Executable via
Download Link: Browser Timer AutoHotKey Source Code