NatACL is a Linux firewall group policy controller for intranets and Internet. Using a internal DHCP server, it can force users to use a DHCP client, and you can block static IPs. It will bind an IP to a MAC address and enforce this usage. You can control groups that can see each other with intranet policies, or control who has access to the Internet. It also has an option to force users to authenticate themselves over the Web before accessing the Internet.
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).
Das Schaefchen is a lightweight HTTP server and proxy for Unix platforms. It supports the minimum requirements of the HTTP/1.1 protocol and virtual hosts, basic authentication (which can be used to protect either files or directories), directory listing, byte ranges, reverse proxy, and FastCGI. It is an event-driven server that runs as a single process with a single thread using non-blocking I/O. It uses epoll as the event notification mechanism to multiplex control between active connections.
Quassel IRC is a modern, cross-platform, distributed IRC client, meaning that one or more clients can attach to and detach from a central core, much like the popular combination of screen and a text-based IRC client, but graphical. In addition to this unique feature, it aims to be a comfortable chatting program.