The name of my new love is Bloom, and it's the best iPhone/iPod application ever. Bloom is the creation of Brian Eno (my musical hero) and musician Peter Chilvers; it makes ambient music that's lovely, relaxing and not tacky with the touch of your fingertips.
The best way to experience Bloom is to find someone with an iPod or iPod Touch, give them $4 and download it from the iTunes Store. Then have fun together.
But, for the curious, I made a video. I've been making music with machines for nearly 30 years and this is the most elegant way I've ever seen. Do you know any other programs out there that do anything like this?