iTunes has long supported half-star ratings, but I recently discovered (I thought) that iTunes 8 added support for setting these half-star values directly within the iTunes interface. After submitting a hint, robg told me that he couldn't replicate the trick, nor could any of the others he asked to also test it out. So I went back to my machine to figure out why it works for me.
After some poking around, I figured out that I'd read about a hidden iTunes preference that enables half-star ratings. After reading about it, I must have tested it, because it was enabled in my version of iTunes (confirmed via a defaults read... check in Terminal). Here's how to enable it on your copy of iTunes. First, quit iTunes, then enter this command in Terminal:
defaults write com.apple.iTunes allow-half-stars -bool TRUE
Relaunch iTunes, and you'll find you can now click between the stars (in the Ratings column) to get half-ratings. If you prefer to drag, you can do that, too, and you'll see the half-star values as you drag across the stars. Very cool; no more resorting to AppleScript tricks to get my half-stars!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20081220090352648