ctrlproxy is an IRC server with multiserver support. It runs as a daemon and connects to a number of IRC servers, then allows you to connect from a workstation and work as the user that is logged in to the IRC server. After you disconnect, it maintains the connection to the server. It acts like any normal IRC server, so you can use any IRC client to connect to it. It supports multiple client connections to one IRC server (under the same nick), allowing you to connect to IRC using your IRC nick, even while you have an IRC session open somewhere else. It supports logging (in any user-specified format), password authentication, and CTCP (in case no clients are connected). IRC servers can be contacted over IPv6 and/or using SSL. Automatic identification with NickServ is supported, as well as various types of backlog.
OperBot is an IRC bot that provides /ctcp INVITE, /ctcp OP, and KNOCK access to a set of oper-only channels. These commands allow an IRC operator to be invited into a channel and become opped in a channel without the bot's administrator managing a userlist. This code is based off the idea of 'son' and 'dth' on EFnet. This code is a standalone C program, and not a script for another client. The code is primarily geared towards "EFnet" IRC daemons, but it works on others.
IRC Chess is a 2-player chess game for IRC. It consists of a Java chess server, with frontend scripts to convert an IRC client into a chess bot. Players then communicate with the bot using standard IRC commands, and don't require any special software to play. Frontend scripts are available for IRSSI and X-Chat.