Extensive High Availability Modules (XHAM) provides “active-active” failsafe solutions to your Linux Firewall, Gateway, Router, Email Server, NIDS (Snort), Proxy, Samba, MySQL (with NAS), and Apache.
Pimp is a modular proxy written in C++ with modularity in mind. So pimp is just a basic proxy and all the protocol logic is implemented in loadable modules. Currently there is a POP3 and SMTP protocol module and a SpamAssassin helper module.