TapSonic

This is a ridiculous app. All it does is allow you to play any number of sounds at the touch of a finger, stringing them together ad-lib to make sequences of arbitrary complexity.

And yet, it's huge fun; and incredibly compelling.

It comes with thirty built-in sounds, and you can also download samples from the web, or record your own, which you can slow down or speed up, add reverb or even reverse. It's like motion capture for sound.

It's also rather fascinating. Did you know, for example, that a dolphin's call, slowed down sounds very much like the territorial noises which some apes make? Or that a dog barking is a really good clue to how large it is? Or even that a simple baking tray being struck, played backwards slowed down with a bit of reverb. sounds amazing?

Apposite Software