See Alk’s comment above, I touched on medical applications.

As for commercial uses, I see very few. These devices are so invasive, I doubt they could be approved for commercial use.

I think the future of Brain Computer Interfacing lies in Functional Near Infrared Spectroscopy (FNIRS). Basically, it uses the same infrared technology as a pulse oximeter to measure changes in blood flow in your brain. Since it uses light (instead of electricity or magnetism) to measure the brain, it’s resistant to basically all the noise endemic to EEG and MRI. It’s also 100% portable. But, the spatial resolution is pretty low.

HOWEVER, the signals have such high temporal resolution. With a strong enough machine learning algorithm, I wonder if someone could interpret the signal well enough for commercial applications. I saw this first-hand in my PhD - one of our lab techs wrote an algorithm that could read as little as 500ms of data and reasonably predict whether the participant was reading a grammatically simple or complex sentence.

It didn’t get published, sadly, due to lab politics. And, honestly, I don’t have 100% faith in the code he used. But I can’t help but wonder.