As of version 4, iTunes has a "Replace Existing" option when users are re-importing CD tracks to replace existing tracks. The problem is that iTunes will only allow this option if the ID3 info for the CD tracks and the current iTunes tracks is identical. This script writes the writable info from selected tracks to the info of a CD; when you re-rip, the CD track data is already the way you want it.
(Note: In order to launch this PowerPC-era script on an Intel machine, it must first be opened and then saved using AppleScript Editor, which is located in your /Applications/Utilities/ folder. More information is here.)
Exports and then re-imports selected tracks' artwork
Set new Last Played/Last Skipped of selected tracks
Create a PDF booklet containing info from the selected tracks
Renumber order of selected tracks
Update subscriptions which have expired by virtue of being ignored for five or more days
Remove iTunes tracks disassociated from files