Site Snitch Description:

Site Snitch helps you keep up to date with changes anywhere in the World Wide Web. You just need to tell what page, image, application or any other resource on the web you are interested and how often you want it to be checked. Site Snitch will do the rest. It detects automatically the most efficient way to check for changes, and notifies you immediately after a change is detected. Site Snitch can follow links inside pages and monitor them as well. So you can easily monitor an entire web site entering only one page. Also, several filter options are available to allow you customize Site Snitch to monitor only the pages you are interested in.