This stay-open applet watches your playing tracks and when an un-rated track starts playing displays a window with a demand it be rated.
While you could easily rate the current track from the iTunes icon in the Dock, this script interrupts you and compels you to do so.
OS X 10.6 or better only. Previous universal version available at the link below in the "Info" section.
This window will pop up when a new song begins playing.
Batch-delete playlists from the selected iPod/iOS device
Append user-entered text to beginning or ending of selected tag of each selected track
Enter text for the selected tracks' Description tag
Display, create text file listing info of dead tracks
Make a text file listing Albums that have some/no tracks with artwork
Remove iTunes tracks disassociated from files