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.
Delete characters from the beginning or ending of selected tracks' name, artist, album, comments, composer, or show tags
List tracks not assigned to playlists
App displays files in iTunes Media folder which are not in iTunes library
Re-associate batch of dead tracks with files from selected folder
Use tag info from selected track to search Amazon Books for cover art
Sort purchased tracks into discrete playlists by name or account ID