Just my support for some previously mentioned suggestions:
-Ctrl+S for strikeout
-Log viewer or RTF/HTML logging
-integrated permanent color changer (not thaaaaaaat important)
-the recent history when opening an im window as in trillian
-(!UPTIME)
-Add notification windows to event logger and to pop checking (i think some programmers who did this would like to help here)
-Quick Sounds panel (such as the quick smilies)
-Divide (!WAT) into smaller tags ( (!W-TITLE), (!W-LENGTH), (!W-PLAYED), etc.)
-Maybe add the possibility to assign a (global) sound to play when anybody logs off? (trillian has this)
and if i think of something else i'll add it