There are so many Web sites that I try to keep up with that it can be difficult to find the time to read them all. There are sites like ChangeNotes.com
that will monitor sites for you and send an email when they find any changes. The bad part about sites like ChangeNotes is that they only check once or twice a day for changes. Just like my RSS feeds I want something that can monitor for changes every 30 minutes. There are two extensions for Firefox that do just that but both are different from each other. Check4Change
(pictured above) allows you to right-click on any site and have it monitor for changes. You must leave the site open to make this work and when it finds that the page has changed it will show the C4C icon on the tab.
The Page Update Checker has the ability to check for Web sites as well but you don’t need to leave the site open. If it finds a change you will see a little pop-up box similar to the one pictured above. It also has a new feature that will try to point out what has changed since the last time you viewed it. I find this extension much more useful than the Check4Change one but it all depends on how you plan on using them. The Page Update Checker is designed more for longterm use while Check4Change is more of a one-time use thing.