Performs a search-and-replace with the text in your choice of tag (Song Name, Show, Artist, Album Artist, Album, Composer, Comments, Genre, or Grouping) in the selected tracks or all the tracks in the selected Playlist. Features case sensitivity and whole word match options and dry run preview.
OS X 10.6 or later only. Previous universal version available at the link below in the "Info" section.
Macworld's Dan Miller has posted a video on how he edits track data using this script.
This window floats over iTunes.