BigBazooka, I switched over to Dalnet for a while there...sorry I missed ya!
Jestin, you can hit the icon "list channels" and everything will come up...you can choose how many people that need to be in a channel for those channels to show up on your list. After you get the list, then you can search within that list for keywords (ie. music, sex, mp3). I started a list earlier that had 5 to 50 people in each channel and I got over 10,000 different channels on Undernet.
mIRC is an ancient program that was originally made for file transferring, but most of the channels now there are for chatting. It's global, so half of the channels aren't even in English. There are different groups within the system...Dalnet, Efnet, Undernet, etc. and within those there are different servers that you connect through. If Joe is using Undernet and Sam is on Dalnet, you won't find eachother. You can privately message people, you can list the names of people in different channels, you can be in multiple channels at the same time, you can have a buddy list, you can see what other channels a person is on, etc. It's not the easiest program to use, but once you figure it out it can be enjoyable.