Check out this neat Menu Bar add-on called I Love Stars:
If you cringe at the thought of having unrated songs in the library like I do, you’ll enjoy I Love Stars. Mainly, it’s there to show the rating, but you can adjust it with the mouse as well.
Reasons to love it:
- Requires very little memory
- Hides self with nifty animation when iTunes is not playing
- Optional alert for unrated songs
- Rate songs with half stars