For those of you who are not yet Orthodox, but would like to explore:
Christ the Eternal Tao, by Monk Damascene – a wonderful book for those who love an Eastern influence and would like to understand the differences between Taoism, Judaism, and Eastern Orthodox Christianity.
A Spiritual Life by St. Theophan - can give you a very good background on the mystical/metaphysical aspects of Orthodox Christianity.
The way of the Pilgrim - has been around for years and this is very good book about the Jesus prayer, which is a very profound prayer we practice in orthodox Christianity. Monk Damascene talks about this prayer in his book I mentioned above.
There’s also little book by St.Theophan called the path of prayer–that presents a very simple way to approach prayer and gives you some wonderful prayers to begin practicing.