Earlier this year, someone from Reddit asked me for advice on classifying some tricky medical image data (CT/MRI/SPECT of healthy vs Parkinson's patients), an area somewhat related to my PhD research. The guy was very knowledgable and had already made a lot of progress. I asked him which lab he was doing his thesis in. He replied to say he was a high school student.

I'm seriously impressed with what these students are capable of these days.