I wish I'd known about this last year when I was writing my thesis. Ear plugs were my constant companion, but this would have been a nice alternative to plug in to.
There are 3 options for noises: white, pink and brown. Brown is my favourite, it sounds almost like the ocean but with a more constant drone, and is even better when you set it on oscillating mode. Auditory zen, indeed.
www.simplynoise.com/