[krozo]

Me, it's http://defonic.com

[moondowner]

http://www.noisli.com/ is pretty good as well.

[tetraodonpuffer]

when not listening to music and needing to drown out coworkers on the phone I am partial to earplugs + http://rain.simplynoise.com/ (it also has an app) I usually take out the thunder which is distracting but the rain itself sounds nice