Japanese researchers may have found a method to determine what you are dreaming about, by measuring brain activity during your sleep.
Japanese scientists can read dreams in breakthrough with MRI scans | South China Morning Post
Read the article carefully, and there are some obvious weaknesses - for one thing, all they've done is data mine, ex-post. Hopefully their next experiments will be to measure brain activity, predict what the person is dreaming about, wake them up, and find out if their ex-ante prediction is correct.
Still, it is pretty darn cool.