The Yumemiru app will supposedly let you control your dreams, or at least what you dream about. From Gizmag:
The app uses a timer and the Apple device's microphone to detect when a user has entered REM sleep, which is when they're most susceptible to dreaming. Then it begins to play a soundtrack for the specific type of dream that the user selects, which could include sound effects or voices directing their dream. The available dreams include walking through a forest, visiting the beach, flying, becoming rich, and even romances specified for both men and women
Yeah, you read that right: "Romances specified for both men and women." If this thing works, that's a billion dollar market right there. Exercises caution though, folks. We've all seen Vanilla Sky.
From the google translation of the Japanese website:
Operation is easy. Only need to specify the time to select the dream you want to see before going to bed, get up. And then put to sleep by my bedside and iPhone, iPhone will detect the state of your sleep, shallow sleep when REM sleep, and play back the voice named after the dreams of your choice.
For example, choose the voice whisper "dream confession for men to be", and pretty women "... I call" will be sent to your ears in a state of REM sleep. I can see a dream that is named after the sound of fun when you wake up in the morning.
So far there are only 8 options available, but if it is open source and app developers get a crack at it options will probably expand rapidly. The first developer who teams up with your favorite pornstars is going to become a very wealthy person.