MyNoise.net is a magical place with sound customizations at every level from sub-bass to high treble. It’s a labor of love by a Stephane Pigeon, a sound nerd who is “signal processing Ph.D. engineer with a strong passion for sounds.”
I use MyNoise.net to focus. It’s been truly amazing how much easier accessing a state of flow has been with the right background noise. I used to use SimplyNoise.com which was awesome until I discovered an entirely new and much more soothing world of sounds:
Experiment first with the full list of sounds and their presets (see “Presets” halfway down any noise’s page on the right).
Let me know if you love it (or don’t) and how it impacts your work flow.