Wikipedia
Moodagent
Moodagent is an automated playlist generator and music recommendations system based on an ability to recognize emotional and musical characteristics of individual music tracks. Moodagent is developed by the Danish company Syntonetic. Moodagent is available as an application for smartphones, tablets, as an online service in Winamp.
The technology behind Moodagent combines digital signal processing and AI techniques to create music profiles that incorporate characteristics such as mood, emotion, genre, style, instrument, vocals, orchestration, production, and beat/tempo.