A while ago, I wrote a short blog post on white noise and binaural beats over at my New Urban Music Blog (German). This peculiar aspect of psychoacoustics is pretty fascinating. Some people use techniques like this to better meditate or concentrate. There is an online white noise generation tool called Simply Noise, so you can get a basic idea of what it's all about.
There are many controversial, alleged uses for binaural beats. Some researchers report that they can influence brain waves and thus help to reduce anxiety. For an introduction on the topic, please read the Wikipedia entry. Binarual beats are also part of a presentation Mitch Altman gave at the 24C3 in Berlin three years ago.
The reason I'm telling all this is that I just found out about the existance of Gnaural, an open source binaural beat sound generator for Linux (and other OSs). Here is a tutorial on how to install it on 32bit Ubuntu systems. If you, like me, have a 64bit system, you might want to follow these instructions. Gnaural offers many options to tweak the generated sound to your preferences, making it easy to experiment with a wide range of differenct noises. Personally, I'm not convinced yet of the method's beneficial aspects, but it's an interesting field if you want to try out some lifehacking