Refuse to Choose by Barbara Sher is one book that has impacted me. It is a book for multipotentialites (aka scanners) and it helped me understand my personality better.
The Bible(s). There are different Bibles with different set of books. I enjoy reading them all and they are a constant source of challenge, inspiration, agony, and encouragement.
Finally, Igbo Olodumare by Daniel Fagunwa is a Yoruba novel of mysterious creatures that exist in a mythical place. The literary style is so rich and invigorating.