I never know that IRC is such powerful thing. I thought that, IRC is only for chatting, just like a chatroom. But I was wrong. Because, I just found that, if you found a correct IRC channel and server that you want, then you can chat and download shared files using CTCP (Client-to-client protocol). And even provide some information such as certain website, certain FTP with username and password, and else, which you cannot find through internet search engine (note: you cannot find them from search engine!!!).
So, for IRC tools, I used mIRC before. But, since I now primarily use Firefox, then ChatZilla is the one.