you know you I was thinking, windows XP comes with a program to add your own unicode characters, C:\WINDOWS\system32\eudcedit.exe, so you could for instance design your own smiley replacement and use a script with $replace to replace them, only problem is that it's quite a hassle while the editwindow doesn't support unicode
although there's always notepad I guess.
Plus there's dll's etc available to do smileys of course, I'm just thinking that this unicode support could enhance IRC in amusing ways..
I tried googling for some UNICODE 'ascii-art' seeing unicode has an abundance of lines and curves characters, but I only found the most basic 2 character things, seems it will take time for people to take to it.
Of course it's hard to show examples in this forum seeing it doesn't suport unicode, but people could put it on sites.