Webtrack tracks the differences on html pages and emails you the diff.
It's written in python (I used version 2.1 on GNU/Linux Debian)
Download the source
where config_file.py is the configuration file
It must be in python syntax, here is example:
toAddress="email@example.com" fromAddress="firstname.lastname@example.org" cacheDir="/home/alain/var/webtrack" tmpDir="/tmp" urls=["http://www.ellought.demon.co.uk/variants.htm"]
The documents are stored in cacheDir, tmpDir is a temporary directory where diff is executed.
You can execute it daily with such a crontab entry:
5 0 * * * /user/usr/bin/webtrack $HOME/webtrack > /dev/null