Bolide Software just announced a new product release named Audio Comparer.
Audio Comparer will listen to your entire audio collection and then will be able to quickly locate duplicates and similar audio files based on their sound, not tags. Currently Audio Comparer is able to locate duplicates among MP3, MP2, MP1, AIF, WAV, WMA and OGG audio files.
Please try this tool and send your suggestions or bug reports using feedback form. Since this is a first public release your feedback is highly appreciated.