I second LETTING GO as a great book recommendation, i have read it 3 times now over the past years and believe it changes me each time i read it.
I would also recommend DEEP MEDITATION by Yogani as a great, quick yet thorough read on how to meditate. It basically outlines the techniques taught in transcedental meditation courses but in a way that i think is more accessible and practical.
Also OUTWITTING THE DEVIL by Napoleon Hill, a book that Ben has recommended before. Another book that i will read again and again.