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.
Make a text file listing Albums that have some/no tracks with artwork
Change file type to make selected AACs bookmarkable
Update subscriptions which have expired by virtue of being ignored for five or more days
Perform search-and-replace on text in your choice of tags
Delete characters from the beginning or ending of selected tracks' name, artist, album, comments, composer, or show tags
Reset selected tracks' bookmark position to their Start Time