I already have the Google Chrome extension that monitors a web page for changes (Page Monitor) - However this extension works on the basis of Regex/Selector input. It might be quite difficult to explain how this works without you seeing it, but I will have a go, using the URL http://www.codingforums.com/index.php:
Selector - #collapseobj_forumbit_1>tr:nth-child(1)>td.alt1
This returns the output "<td class="alt1">71,147
</td>" i.e. it directly monitors whether there is any change in the number 71,147
Regex - \b71,147\b
Selector - #pages>strong
returns the output "<strong>Results <span id="pages_count"></span></strong>"....
However, when the "pages_count" actually changes e.g. from 10 to 11 for example, this is not picked up by the selector expression because the "pages_count" statement remains constant, even though the underlying data has changed (if that makes any sense whatsoever).