PAW (pro-active Web filter) is a filtering HTTP proxy based on the Brazil Framework. Because the Brazil Framework and PAW are written in Java, the software is highly portable. PAW allows for easy plugin of Handlers (to filter outgoing requests) and Filters (to filter incoming data), and a GUI for end users. All the configuration files are in XML, and thus easy to modify (even without the GUI). It's aim is to provide an easy to use interface for end users and to be easily extendable by developers.
mod_sphinx is an Apache module which intercepts output bound for the client, whether it be from files served by the same Web server, files sent via reverse proxying, or files delivered by transparent forward proxying (outbound proxying, as in your browser's proxy setting). It opens the text and replaces a word with another word or phrase. When in regular proxy mode, it cannot modify SSL content since Apache cannot decrypt that (it would be a protocol violation).