I am orphaning websec, here is the description:
Web Secretary is a web page monitoring software. However, it goes beyond
the normal functionalities offered by such software. Not only does it detect
changes based on content analysis (instead of date/time stamp or simple
textual comparison), it will email the changed page to you WITH THE NEW
It is a small but very useful package, which is unmaintained upstream.
I have kept it inside debian, because users still request for small changes
now and then.
You will need a bit of perl knowledge to maintain it.