Do you mean Keyboard Launchpad?

I don't know if this works with iTunes, but I use mp3 gain http://download.cnet.com/MP3Gain/3000-2169_4-10367823.html to normalize all my mp3s.  I use it with Winamp.  I totally got rid of iTunes -- it's ugly, it can't be skinned, it requires Bonjour Service which slows down startup time, and heaven forbid something happens to your computer, then you're stuck not being able to transfer your tunes onto a new computer -- Winamp just has so much more and is so simple.  Because I sometimes listen to music while I'm working (and my job consists of listening to dictation and transcribing it), I have a special equalizer setting so that the volume is ultra low as background music.  I'm not sure you can save equalizer settings in iTunes, but I believe it DOES have an equalizer you could set for a lower volume than the rest of what you have open.

Yeah Launchpad.

Yeah, itunes isnt the best program, but I dont use it for anything more than an mp3 player and my playlists are already established on it.  I have bonjour completely disabled from startup.  Anyway, I still want to be able to control the volume of the media playing programs independent of the system volume for the reasons stated above.  Like I'll simply be playing an RPG and combat will be going so music will be up fairly loud.  Then combat finishes and there is dialog but I can not hear what is being said because the music is too loud.  I suppose I could simply pause itunes (which doesnt always work for all games using kbl, but I'd still like control over the volume of individual programs.

As for normalizing MP3s, I've tried that several times with negative results.  It tends to quiet all of the MP3s to a degree that even the max volume on itunes and the system is too quiet to hear anything.