[namlem]

Some sort of inexpensive, portable neuro-imaging device could be huge. It would allow us to interact with technology almost seamlessly, and solve a lot of problems. If it becomes ubiquitous, it also solves almost all out security problems. Brain-based biometrics that work by measuring your brain activity while you look at a particular image. Unlike other biometrics, it's easily cancelable and extremely secure. You can change your "password" by selecting a different image.

It would also grant us the ability to much more effectively monitor our mental state. I bet it could be extremely helpful in combating anxiety and promoting mindfulness.