k-IRC is totally free java-based mobile application (client) for connecting to any IRC server. It will execute on any handheld device or mobile, supporting Java 2 Micro Edition (actually CLDC1.0/MIDP1.0). k-IRC allows you to login to an IRC server, enter multiple channels at the same session, talk in the channels and with individuals and receive others' messages and easily keep the track of active channels and switch between them.

Link: http://kirc.armondavanes.com/

Free J2ME based IRC Client. Its a very simple piece of software with no frills. The interface is text-based and very simple and setting-up a connection is easily done. You can't see what people are saying while you are typing a message. Features: Multiple windows, Profiles, for using multiple servers without having to type the host/nick each time, Scrolling, UTF-8/Cyrillic/Russian codepages supported natively, Open Source

Link: http://www.vidarholen.net/contents/virca/

IRC MIDlet for mobile phones. jmIrc is a J2ME MIDlet allowing ie. cell phone owners to use IRC wirelessly. It should work on any device supporting MIDP 1.0 and also supports connecting through HTTP proxy server on phones that don't support the Java socket API.

Link: http://jmirc.sourceforge.net/

WLIrc is a free IRC Client for Java cell phones or any other device who support java MIDP 1.0. WLIrc is almost identical to Virca. It has a very similar UI (text-based) but uses colour instead of the depressing black and white that you have with Virca.

Link: http://wirelessirc.sourceforge.net/

WirelessIRC is a native IRC client for your Nokia 3650/7650. You can chat with thousands of other people online or exchange images, voice notes or other files.
WirelessIRC connects you to any IRC network while you're on the move. Be in touch with your friends everywhere at any time. WirelessIRC supports DCC file transfer. You can receive files from other people on IRC. Images can be viewed or saved and you can listen to sound files or install them on your phone. WirelessIRC really is a fully blown IRC client with lots of handy features and a built-in file-browser, help-system, data-counter and more.

Link: http://mobileways.de/M/1/4/0/