If you are struggling with the new low-contrast icons in iTunes 10, here is a hint to change the appearance.
In the terminal enter:
defaults write com.apple.iTunes high-contrast-mode-enable -bool TRUE
This will give a high-contrast side bar and listing pane. To undo this repeat the command but change the TRUE to FALSE. I haven't managed to get the color icons back yet though.
The preference AppleAquaColorVariant is next in the list after high-contrast-mode-enable and also does something, unfortunately every value I've tried so far prevents iTunes from launching. If you want to experiment, you can remove it to fix iTunes with:
defaults delete com.apple.iTunes AppleAquaColorVariant
[crarko adds: I tried this, and what it does is go from black on white to white on black. That certainly is higher contrast but I don't know how appealing that will be. I may try it for a while. If anyone has success with the AppleAquaColorVariant setting please submit a hint about it. That would seem to be a more desirable change.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20100903144502831