Psotnic is a mature IRC bot, mainly written for the IRCNet network. Latest snapshots should run on the most common networks without big problems. It is written in C++ featuring a fast C++ module API. The bot is able to form botnets with a hierarchical structure, with blowfish encryped bot-to-bot connections as well as encrypted userlist and config file.
At one point, Open Hub analyzed source code for this project based on code location(s) available at that time. Since then, the code locations have been removed.