Lets add a few more that may be of interest. One of the more powerful books I have read is "A Handbook of Spiritual Psycholog
y" (ebook). This is one of the few books that can be considered to be really powerful. One more that may be of interest is "Light Seeds" by Michael St.Clair. It hard to describe, but its a kind of fact/ fiction type book. Youll have to read it to understand that though.
I have read the Kybalion which is more of an occult book, but good reading if you are into psychic areas. I remember it is quite heavy reading though. Its on the web somewhere.