This script checks your entire iTunes library for missing and presumed dead tracks--those tracks that iTunes is unable to associate with a file and which are listed in iTunes with a "!"--and can create a text file listing these tracks by alleged File Path (if available), Song Name, Artist and Album, which you can view using TextEdit.
OS X 10.6 and later only. Universal version for PowerPC machines available at the link below in the "Info" section.
Also see Music Folder Files Not Added
To find and delete dead tracks see Super Remove Dead Tracks.
See the video on YouTube.
iTunes can't find the files pointed to by the Location property of these track entries.
Update subscriptions which have expired by virtue of being ignored for five or more days
Delete characters from the beginning or ending of selected tracks' name, artist, album, comments, composer, or show tags
Perform search-and-replace on text in your choice of tags
Sort purchased tracks into discrete playlists by name or account ID
Perform various tasks on a selection of playlists; rename, delete, duplicate, merge, more
Make a text file listing Albums that have some/no tracks with artwork