IMIRC is an AOL Instant Messenger to IRC gateway. It connects to an IRC network as an IRC server, so it requires a local ircd to run. IMIRC creates nicknames for AIM users as they sign on, and converts HTML codes, which are used by AIM for formatting, to IRC's control code equivalents. Please note that you must either have your own working IRC server or you must find someone willing to let you link to theirs.
CGI:IRC is a Perl/CGI program that allows you to use IRC from a Web browser without having to have access to an IRC port. It does not use Java, but it does need a browser capable of rendering frames. It can be used on a Web page to allow users to chat, or it can be used to access chat from behind a firewall.
DarkFire IRCd is an efficient, modern, and flexible IRC server used primarily on the DarkFire IRC Network. Originally based on Dreamforge, it has numerous enhancements and a wider variety of features. It features an efficient server to server protocol, a wide variety of user and operator commands, and a flexible protocol.
Datasphere is a conferencing system that was designed to overcome some of IRC's largest problems (scalability, no mesh routing, flat channel structure). It provides a usenet-news-like channel structure, a TCP level multicast implementation over a mesh of TCP links, a distributed channel- and user database and much more features. But most important of all. it's IRC compatible at the client side. Currently basic chatting functionality works, dynamic rerouting works, but progress is very slow.