I got this from Macfixit.com, an invaluable resource for Mac users, especially those of us who have to be our own IT departments. The original article is no longer available for non-subscribers, but it’s too good a tip to let pass.

I find the star ratings in iTunes pretty helpful. With 8776 songs currently in my library, it’s easy to forget there’s a particular song I liked or disliked. Not to mention it’s nice to tell iTunes to only play songs rated 4 stars or higher, on one of those stressful days when you could use a lift.

The problem is, 5 stars aren’t enough. For me, a rating of 1 or 2 stars is a negative rating, so that leaves only three levels of the songs I do like. I think an average song should be 2.5 stars, not 3. Three should be for songs you’ve heard once and think maybe you’d really like them if you heard them again, as opposed to the songs where you think, oh, that’s an average song.

It turns out that you can enable iTunes to show half-star ratings. This is a Mac-only tip, because you have to go to the Terminal program (the Mac’s Unix command-line interface) to enable it. I imagine there is something similar in Windows, but I don’t really know.

Anyway, it’s simple. Quit iTunes. Open up Terminal (it’s in the Utilities folder in Applications. Or shift-command-U in a Finder window will take you directly there). Type the following:

defaults write com.apple.iTunes allow-half-stars -bool TRUE

Relaunch iTunes, and there you go. Macfixit notes that contextual menus or the application menus still will not let you rate half-stars, as these are hard-coded in the application as full-star increments only. You have to click in the star ratings in the iTunes window. Whatever—it was news to me that you could even do star ratings via menus.