Archangel
A flexible, extendable content filter
...It is basically dansguardian rewritten in python as an ICAP server as opposed to a proxy front-end. The benefits of archangel over dansguardian include:
1. Because it is an ICAP filter, it interfaces with squid and can do HTTPS filtering as well as regular HTTP.
2. Because it uses blocking modules and is written in python, it is extremely easy to write new modules for very complex, intensive blocking. I have already written a module that does content-based blocking of youtube videos.
Archangel uses the pyicap library to implement the ICAP functionality. The blockpage requires use of the PHP 5.4.x CLI. ...