Some years ago, my friend Zarf created a...thing...called Boodler. Boodler was a python-based soundscape tool that would put together programmatically generated soundscapes at your request; so you could tell it "Play a loop of crickets" or "frogs" or "wind" or "ticking clocks" and it would. Of course, it required someone to actually write a little python script to provide the rules by which the soundscape was generated, and you had to install the required sound loop packages.
One particularly good soundscape, contributed by Owen Williams, was a 1-hour thunderstorm.
It was a pain-in-the-ass command line tool that I had to look up the various arguments to every time I wanted to use it. But the 1-hour storm was so good that, for quite a while, I would set it up at bedtime and use it to help me go to sleep.
When Zarf started doing iPhone projects, we had conversations about Boodler. He was of the opinion that it was too complicated to do a general-purpose port. "Dude,"1 I said,"Just make an app that plays that thunderstorm. You'll make millions."2
Tonight, he has released...Pocket Storm.
$2.99. A thunderstorm in your pocket. I've been beta-testing this, and, what can I say other than: I won't go to sleep without it. The thunderstorm is actually somewhat different than the one that shipped with Boodler, but it's just as good, in a different way. You can vary the speed at which the storm crests and abates, and you can have it play forever, or stop after a certain number of minutes, or – my favorite mode when using it at bedtime – have it stop playing when the storm is over.
It's a beautiful little app that does only one thing, and does it exceedingly well. If the idea of having a wonderful, never-ending thunderstorm to listen to whenever you want appeals to you, you need this in your life.