Namaste christine,
thank you for the post.
generally speaking, i would tend to explain the thrid eye from the point of view of the Chakra system which is fairly prevalent throughout the Dharma traditions.
the Chakra systems are somewhat different amongst the various Dharma traditions, however, this is mostly due to using different terminology and different axioms which are held by the practiconers.
within the context of Tibetan Vajrayana praxis, the pineal or third eye isn't even used

in this system, it is the Crown Chakra at the top of the head or, as we say the Mahasukha Chakra. this Chakra is related to the body and activity and represents a fairly substantial departure from the Sanatana Dharma Tantric systems.
there is an excellent book on this, from the Tibetan view, called "The Clear Light of Bliss" by Kelsang Gyatso which may be of some interest.
http://www.amazon.com/gp/product/094...Code=kheper-20
metta,
~v