Syntonetic has launched Moodagent—a recommendation/playlisting app based on a user’s mood and emotion—for iPhone/iPod Touch. They have a Nokia smartphone version too, dubbed Playlist DJ. Moodagent syncs with an existing music library and users adjust moods with five sliders—sensual, tender, joy, aggressive and tempo. The app profiles tracks based on these mood indicators, and users can create playlists based on combinations of moods and emotions. Moodagent is free for a limited time in the iTunes store. Try Moodagent or Playlist DJ when you’re “in the mood” and give us your review.

Mood-based technology might zap us to better understand how music relates to human emotions. In their press release, Syntonetic says they’ve “cracked the emotional codes found in music to create an intelligent system that deciphers every musical property in a song, including moods and emotions, as well as musical genres and sub-genres, styles, tempo/beat, vocals, instruments and production features.” The way I see it, we’re only on the brink of emotion technology. App enthusiast Diego Balbuena says, “I do think that these type of programs can be the next killer app” but he stresses the importance of the apps being human-like. The more users that use the app, the more data they’ll have, and the better the algorithms will be. Happiness is a warm iPhone.