beaTunes is an iTunes companion app capable of automatically analyzing your music collection to help you build better playlists. It analyzes BPM (beats per minute), silence at the beginning or end of a song, and the color (based on frequency spectrum) of a given song. Some of the data is stored through iTunes, and some is stored by beaTunes itself. beaTunes can suggest albums that would complement your music collection, display music charts, and help you find and fix errors in your song meta data, like typos and wrong genres. It also allows you to blog about selected songs or playlists.
pHash is an implementation of various perceptual hashing algorithms. A perceptual hash is a fingerprint of a multimedia file derived from various features from its content. Unlike cryptographic hash functions that rely on the avalanche effect of small changes in input leading to drastic changes in the output, perceptual hashes are "close" to one another if the features are similar. Potential applications include copyright protection, similarity searches for media files, or even digital forensics.