Behold! The Zealot Speaketh unto TheeSo it's about time I mentioned
XChat. This multiplatform irc client is free (yes even the windows version is free!), and supports many scripting languages: last time I counted it was seven but it seems guile has been added, so that makes
eight supported scripting languages! Mirc-Scripts are not supported at all, but you can choose from perl, python, javascript, tcl, ruby, lisp, guile, and C.
IMNow, if you want to "do instant messaging" as well, there is
bitlbee which works with
every irc client. It functions as a gateway between irc and IM. Bitlbee has been working reliably for over four years here.
-ismIf you want a little minimalism I believe xchat+bitlbee make a very good combination: bitlbee has no gui at all; xchat's interface can be reduced to the bare chat necessities. I have attached an example screenshot of how it could look.
On the other hand, if you prefer all sorts of gui widgets and stuff, xchat can do that as well; I don't have a screenshot as proof though...