CBM Filefinder 1.0 by AEG software (2009) - This utility is one of my go to programs when I'm trying to find a file with a particular filename or even a partial filename that could be somewhere inside of 100,000+ .D64 images.  You can search through many different disk image formats and even search directories recursively.  The only issue I've found with this utility is that it has trouble when the full path to a file is quite long.