Before diving in and spitting out this package I looked at the alternatives below. If I have missed something please drop me a mail.
It isn’t meant to be unbiased, and you should try the packages out for yourself. I keep it here mostly as a reference for myself, and maybe to help out people who are already familiar with one of the entries below so they can see where I’m coming from.
ck4up is a small tool written in Ruby which scans webpages for updates by storing the hash of checked pages. It provides pretty much the same functionality as cupage, but in a slightly different manner.
The major differences are a lack of HTTP cache support, a more manual configuration method and no built in support for various hosting sites.
urlwatch is a great little tool, which sends you emails containing the differences in web pages. To some extent cupage is mostly a narrow subset of the functionality provided by urlwatch, and the functionality could have been implemented on top with a bunch of hooks.
In my opinion the disadvantages are a lack of HTTP cache support, the configuration requires users to write Python and no built in support for various hosting sites. The massive advantage is how configurable and hackable the tool can be thanks to the “config is a python script” design.