I often make the decision to buy a certain product, a PC game for instance, when it drops below a certain price that I'm willing to pay for it.
While I could check for price changes manually on a regular basis, I prefer to use a program for the tracking and monitoring. This has several advantages, including saving valuable time and immediate notifications when the price drops.
AlertBox is a free Firefox add-on that can be used to monitor any changes on Internet web pages. You can use it to monitor price changes on Amazon, new replies or posts on your favorite web site or new public photos on a user's Flickr photo stream.
Configuration of elements that you want to monitor is simple and straightforward. All you need to do is to select the element on the page that you want to monitor, right-click and select AlertBox > Add alert for changes in clicked element.
The extension can not only monitor specific elements on a page, but also the page as a whole. This is done with a right-click anywhere on the page and the selection of the option under the Alertbox context menu entry.
The Firefox add-on displays a notification whenever one of the tracked elements or web pages gets updated. The notification leads directly to a page where the changes are highlighted. These changes are displayed as a history on a local page in the browser.
Another option to configure the monitoring comes in the form of the Alert Config Panel. This panel can be opened with the shortcut Ctrl-Shift-z or via Alt-key > Tools > Alert Config Panel. It opens at the bottom of the all pages that are currently open in the web browser.
All page elements become selectable right away on left-click for as long as the panel is open in Firefox. The panel offers more options, including one to select the default interval in which the select page is checked for updated contents.
Experienced users can switch to an advanced view which allows them to select any script, CSS or HTML code in the source code of the page and combine that with content filters for advanced tracking operations.
The extension's settings are only linked on the monitoring page where all tracked pages and page elements are displayed. Here it is possible to configure different notification types, e.g. sound notifications, and to register an account to enable email notifications.
Users can last but not least configure the update check interval on the page for all tracked elements and web pages they have previously added, check the most recent version of the web pages that they monitor.
Firefox users who are looking for an easy to use extension that is offering them advanced feature if needed should take a closer look at AlertBox. The extension can be installed from the official Mozilla Firefox add-on repository.
Update: AlertBox has been renamed to Distill Web Monitor.