I've been thinking a lot about BCI and decided to look a bit more into EEG stuff. I don't actually work with EEG waves but I do work next to an EEG lab and pestered a bunch of people on my lunch break.
The good news is that they totally can't read our thoughts. Not even close. The brainwaves that EEGs can pick up are very broad and really just give a general idea of brain activity. It can tell if you're asleep, awake, alert, relaxed, or deeply relaxed based on the frequency of brainwaves. I'm totally oversimplifying and there's lots of other stuff but this is basically the nuts and bolts of what EEGs are picking up:

Companies and the media are always real quick to use words like mind reading and make claims that it can read your emotions or see your dreams but its basically just pattern recognition. They will ask you to think about something sad, pick up the readings, and then later when the program sees similar patterns it assumes you are sad. This sort of thing is iffy in a controlled research environment and tends to not work at all out of one. So, while amazing (and totally useful for a variety of medical stuff) it's not quite as amazing as actually reading thoughts although Darpa is trying to push the boundaries.
http://www.digitaltrends.com/cool-tech/this-is-your-brain-on-silicon/Neurofeedback is another application that is still in its infancy. Even in the EEG lab next door to where I work people can't seem to agree whether it works or not. I keep looking at scholarly articles and it seems that the answer is a resounding 'Maybe' One thing they do agree (as much as doctors can anyway) is that it is possible to alter your brainwaves and this has been studies many times with monks and meditation.
http://www.washingtonpost.com/wp-dyn/articles/A43006-2005Jan2.htmlNeurofeedback in the medical settings mostly focuses on an alternative to drugs for ADHD. In ADHD there tends to be an abundance of theta waves and less beta waves. In theory by using biofeedback the patient can learn to control these waves and learn to increase their focus. Some doctors think this works, other doctors think it doesn't, and there is an alarming amount of absolute crazy people who think neurofeedback can cure everything and that it can give us superpowers. Which leads me to horrible use number 1. Oh and there is some good data that about 1 percent or so of people who use neurofeedback go insane so.......there's that too.
1) Changing the brain: So we know we can change the brain, but we aren't certain what it will do. For example an abundance of Theta waves tends to be present in ADHD but we also know that it is associated with creative activities such as art. The potential to 'cure' the next Picasso is certainly there. Even more scary is to think about it being forced upon mental patients to 'correct' irregularities. Also there are people who claim they can utilize neurofeedback to achieve a state of bliss and ecstasy and/or hallucinate without drugs, which kinda sounds neat but can also go wrong in a wide variety of as yet unknown ways.
2) Brain Profiling: There are some researchers that believe that EEG will eventually be able to identify 'deviant behavior' This could lead to people incarcerated or denied jobs due primarily to their brainwaves. "I'm sorry, but Wal-Mart can't hire you right now. You exhibit too many theta waves. Perhaps you can check yourself into a reconditioning center and apply again next year."
3)Mind Reading and Privacy: Currently they can't read minds but that doesn't mean they aren't trying (Actually in the US I'm reasonably certain they never stopped). One implication is that even assuming your BCI is under your own control that hackers could create spyware that attempts to read your brainwaves. Currently not a whole lot they can do with it, but its a scary thought. A short article about the possibility:
http://gizmodo.com/5938279/researchers-are-trying-to-hack-your-brain4)Marketing: While reading emotions is still extremely unreliable and murky there are possibilities for companies to customize products depending on EEG readings. A benign form would be a program that links with pandora radio or itunes and selects music based on algorithms of previous recordings. A more monstrous form would be a movie theater full of people wearing headsets that gives information about what people find funny, scary, or endearing. As if entertainment hasn't been homogenized enough. I'd like to think that humans wouldn't volunarily wear a 'squid rig' in order to give corporations their brain data but.......aw, who am I kidding. They'll line up for the chance.
5)Mind control and interrogation: If brainwaves can change, what happens if it gets a pulse that attempts to forcibly change the waves. I have to admit I know less about this since most of my job is picking up waveforms rather than giving them. However there is evidence that it might be possible. Since 1839 there has been evidence that things such as binaural beats can affect the brain. This and similar techniques were used in attempts to induce lucid dreaming. The potential is certainly there for mind alteration as well as advanced interrogation techniques.
http://en.wikipedia.org/wiki/Binaural_beats6)Neurotheology: This actually isn't new and the field ranges from the somewhat scientific scan of chanting monks brains. To things like this:
http://en.wikipedia.org/wiki/God_helmet. Yes, that is what it is called. The God Helmet. As crazy as it sounds there just might be something to it. However, as I said before there are a whole bunch of seemingly unhinged crackpots that are involved in pushing the limits of BCI. This field may produce good things or it could produce some really really messed up fundamentalism. Here is a long article if anyone wants to find out more:
http://www.npr.org/2010/12/15/132078267/neurotheology-where-religion-and-science-collideFor more info on ethical considerations I would suggest this short scholarly article here:
https://landing.athabascau.ca/file/download/110427I'm sure there is more that I haven't thought about and I'm sure I both glossed over much of the finer points of EEG (as well as totally not being an expert in the field) but BCI seems to be as horrifying as it is amazing. Still, the toothpaste isn't going back in the tube so whatever the future holds we're going to have to deal with it. There is massive potential to improve the quality of human life but also the potential to create horrible horrible dystopias.
Currently around 95 percent of the research into BCIs is in the medical prosthesis field. It can make robot arms work. It can allow paralyzed people to communicate. It can do some really really good beneficial things for folks.
After all, what can possibly go wrong with prosthetic limbs?