The Monroe Institute sells a series of audio clips that emit a different tone in each ear with which the brain creates a third oscillating tone. This third tone is known as binaural beats which they allege to synchronizes the brain's hemispheres.
The series is called the Gateway Experience. Its a kind of semi guided meditation using the binaural beats that is intended to induce out of body experiences.
I tried it years ago and although I never experienced a OOBE it did seem to induce lucid dreaming. Its a bit new-agey but not in a preachy or religious way.