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.)
Re-associate batch of dead tracks with files from selected folder
Create a Ringtone track from a selected track
Resample selected tracks' artwork to user-set size limit
Applet assists with swapping, copying, appending data between track tags
Edit a selection of iTunes tracks' tags in single window
Deletes the current track from all playlists and moves to Trash