X-Chat Aqua is a very nice IRC client for Mac OS X, but the latest version for download on their website is way out of date and a few years old.
A while ago libc volunteered to import the old CVS into a new SVN repository and started development on it again. So the version in SVN is now based on xchat 2.8.x, but there are still no binaries available.
Therefore I just put together my own build and I am also offering it as a download for everyone. The application bundle contains an Universal binary for both PowerPC and x86, while I was only able to test them on Leopard.
Download X-Chat Aqua: xchataqua-2009-01-21.tar.gz