I've been using binaural beats as an aide for meditation. I haven't yet decided if they are closer to homeopathy and angel healing or academic neuroscience. If nothing else, they seem like a a harmless tool to block out sound.
Binaural beats - according to research and Internet
Binaural beats were discovered by a Prussian physivist Heinrich Wilhelm Dove in 1839. Immediately, people on the Internet tried to get high on them.
The idea about binaural beats is to play two different tones into separate ears, so the end result is interpreted by the brains as a single beat with Hz common to brain waves. This beat is then supposed to sort of trawl brain waves into the same area as the beat. So if you play Theta area binaural beats (4-7Hz, deep relaxation and increased learning), your brain waves should follow suit and you should relax.
The website Gethighnow.com lets us know that even if binaural beats have been used as cure-alls for everything from impotence to bulimia (just like healing crystals, for example), it's all cool because binaural beats are Science.
There have been some studies made on binaural beats and they have found that brain waves follow the beats. Still, those have been with samples of about three people and often flawed research methodology (See for example wikipedia.) Skeptoid.com also has a small article on how binaural beats are probably about as good as any sound or music.
Basically, whatever works, or whatever.
Binaural beats - personal experience
I've been using binaural beats as an aide for meditation during Hacked Man and they have seemed maybe even helpful. At least they block out sound in an non-disruptive way. If meditating in a place where you want some simulated privacy, this might be useful.
Not sure if they do actually help or hinder concentration or reaching enlightenment. I'll have to try to meditate some more without the beats just to make sure. They could have a helpful placebo effect (which is powerful and real, never knock placebo), but I can easily imagine they could also turn into a hindrance or limiting factor at some point later.
I tried to write this post while listening to some high activity concentration beats. Those mostly seemed to hurt my teeth and my concentration was all over the place, so had to turn them off. Maybe I won't be using those frequencies anymore.
I haven't tried using these to fall asleep (another thing that these are often used on) as I don't really have that much trouble falling asleep usually and don't have earphones that would be comfortable to sleep in any case.
Hum, sort of useful maybe if you aren't disturbed by a constant high pitched drilling and whining noise in your head. Activity induced noises obviously aren't for me and probably classical music works better for relaxation also. Still, when I want something absolutely non-disturbing and nicer than plain white noise to block out stuff, I can use binaural beats.
I've been using Giorgio Calderolla's Binaural for iOS for playing beats. Even if you don't care about binaural beats, you should check the app out. It's free and beautiful and wonderful to use.
These kinds of apps are what make me like Apple stuff. I haven't probably seen a single app on the Android side with this kind of user experience and design.
P.S. Gethighnow.com also offers a beat called Roommate Annihilator, so they can't be all bad.