playing around for a bit gave me this...
iTunes/Contents/Resources/English.lproj/Localized.rsrc
iTunes/Contents/Resources/iTunes.rsrc
both can be opened with a resource editor like Resorcerer for os x, and with some looking and playing you can change font options, just about every graphical aspect of the application - altho be wary, it takes a lot more time to execute something properly than fsck something up totally, and with the amount of graphical resources in iTunes get ready for a huge undertaking.
if anyone has any problems or any questions just toss me a private msg, I hack around with resources in just about every app and don't mind serving as a sounding board as I'd love an aqua pinstriped skin but hardly have the discipline to do it