Aside from modern eastern medicine and it's extrapolated fields, the pineal is I believe related to the Third Eye Chakra. Many theories have been suggested based off the notion that the pineal gland in reptiles seems to have some sort of optical lens, though my memory is a bit fuzzy. Descartes was one of the more recent Western thinkers to apply mystical abilities to the the pineal gland. As far as modern discoveries, I really don't know much besides wikipedia haha.
This link includes some of Descartes speculations, which are interesting, but not exactly grounded in much in terms of evidence. But it's interesting from sheer historical perspective.
Descartes and the Pineal GlandThe pituitary gland is just as mysterious as the pineal gland in my opinion, and due to their connected location at the center of the brain I personally believe they have important roles of messenger/receivers, and perhaps regulate some sort of neural chemistry distribution. Though I'd also love to hear further responses in this thread from people with more sophisticated anatomical knowledge on their known functions.
The only hell for a warrior is peace.
The warm fuzzy side of the cold hard truth.