iTunes Library Check 1.2Free
iTunes Library Check cross checks your iTunes Library for unlisted files in iTunes.
It scans the iTunes music library and checks if the found files are referenced in iTunes xml file. All unreferenced files are listed in the "Extra files" tab view and all references that lacks actual files are listed under the "Missing files" tab view.
What's new in this version:
Does not count iPhone Ringtones (which I figure iTunes handles differently).