cl-irc comes with two example bots: clhs, a bot which performs hyperspec lookups, and cliki (aka minion on #lisp), an infobot that uses CLiki as a second-level database.
An IRC bot that listens for connections through the web and allows users to paste text into a webform. A link to the webform is then displayed on the selected channel.
A multi-channel logger with web interface.
WMBot is a base that connects to the IRC server and responds to PING messages, and a set of modules that can be enabled and disabled while the bot is running. Currently implemented modules include basic logging, basic user management, a command module, and a simple info module, and it is fairly easy to write a new module. There has not been a packaged release in a while, but the svn repository at sourceforge.net has the latest code.
"The Lispbot is pretty much what it sounds like. It is an IRC bot written in Common Lisp. It doesn't do things like OPing and kicking flooder, other bots do that just fine. Rather, it provides some structure for other applications that users might want to interact with over IRC. Main feature is "eval" which allows commands to be used in a channel and executed in the main lisp system with the output going back to the channel."
Eval Bot is an REPL for IRC channel. It evaluates Common Lisp expressions and sends the values back to the channel. A subset of Common Lisp features is supported.
Lisp IRC Bots
There are several IRC bots written in Lisp. Most of them these days are done with the cl-irc library, which handles all of the IRC protocol (including DCC) and presents a very nice CLOS interface.