Binaural: relating to, or having, or hearing with two ears.
.wav: short for Waveform Audio File Format, is a Microsoft and IBM audio file format standard for storing audio bitstreams on your PC.
“Binaural Beats or binaural tones are auditory processing artifacts, or apparent sounds, the perception of which arises in the brain for specific physical stimuli.”
Binaural waves work like this; each ear hears a difference frequency. Each tone reaches the brain at the same time and the brain creates a new frequency that is the difference between the original two. The frequency that the brain makes simulates a desired effect.
If you are looking for some more info just Google search Binaural Tones; you should get a decent return.
UPDATE January 09, 2013:
I found a great sight for free binaural downloads; http://free-binaural-beats.com/tone-database.