In iTunes 10, the icons in the sidebar have gone from colourful to drab light-grey; to some eyes, that change makes the icons harder to distinguish. If you’re one of them, you might be interested in a tip from an anonymous Mac OS X Hints reader that implements an alternative colour scheme:
If you are struggling with the new low-contrast icons in iTunes 10, here is a hint to change their appearance. After quitting iTunes, open Terminal and enter:
defaults write com.apple.iTunes high-contrast-mode-enable -bool TRUE
When you restart iTunes, you’ll have a high-contrast sidebar and list pane. To undo it, repeat the command but change the TRUE to FALSE.
By “high-contrast”, this tipster means “stark black and white”. Many users who have tried this tip say they like the results less than the new all-grey and so undo it. It doesn’t look great in the new default Album List view (View -> As Album List or Option-Command-4); it looks better (relatively speaking) in plain List View (View -> As List or Option-Command-3).