In my spare time I am developing a more complicated notifier with a web interface. The additional feature is that it let's you add some regexps to ignore some changes (it is usefull for pages that for example show current date somewhere). I plan it to evolve into something like what RSS does by extracting what is new on the page (with a kind of HTML diff). You can read some documentation for that, download it or try it on my home server at Active Bookmarks Manual.

I wanted to use it as a replacement for Personal Nodelet - so it has a special (undocumented) feature that links to Perl Monks are internally converted to links to appriopriate The Pen pages.

By the way most current web browsers can notify you about changes to pages in your bookmarks.