IRC Channel Relay Bot allows you to have an IRC channel span multiple IRC networks. It relays public and private messages, informs you about people joining and leaving the channel, and passes topics across networks (if you op it). It has minimal ability to help protect the channel.
PimpBNC is an IRC bouncer written to be easy to use and still have many powerful features. It supports Perl modules, runs on almost any platform, supports multiple clients sharing the same nick (IRC-NAT), and has a Web-interface to ease configuration, feedback forms to ease reporting comments or bugs, many detailed configuration options, an away system with logging, feature to automatically update whole or parts from the Web while running, and the ability to notify the user when updates are available.
Atheism is an extremely flexible, configurable and user-friendly multi purpose Perl script for X-Chat. Its main features include auto-away functions with message logging, announcement of songs playing in XMMS on selected channels, a user-friendly interface, detailed documentation, and much more.
SorIrcd is a relatively stable IRC daemon derived from dal4.4.10 which was based on irc2.8.mu3. SorIrcd's features include open proxy detection, HUSH and UNHUSH commands for silencing flooders, IP address hiding, oper channel mode hacking (option), logging of network events (like mode hacks), and a number of other extensions.
Eddie's Extensions are TCL scripts for an eggdrop bot to add extra features, including a magic 8-ball, polls, random numbers, whacks, calculator, locking channels, insult generator, and various quirky features. It also has the option to let your eggdrop limit the channel on which it's staying, which will enhance the protection of the channel.