Talk about options! There are many many many IRC apps for OS X. For command line, there's IRCII (the original), BitchX, Irssi (my favorite ), xchat, and probably more. For GUI, there's IRCle, Snak (the two most popular), XChat Aqua, Colloquoy, Irssi Mac (a tad rough around the edges and a pain to configure), and a bunch of others that few people use. There are also apps that connect to one network only and are associated with Web forums and such.