If you’ve never read his book The World’s Religions (originally titled The Religions of Man) you ought to put it at the top of your list. It was the first of its kind and maybe still the best, a sympathetic yet scholarly account of Hinduism, Buddhism, Taoism, Confucianism, and the Abrahamic faiths. (The 1991 revision added a short section on the “primal religions”, the non-historical traditions of indigenous peoples, which is not as strong as the rest of the book — but that is a high bar to meet.)
As Jeffery Paine, who helped with Smith’s autobiography, put it, “Huston showed a new way to be religious. While remaining a devout Christian his whole life, he practiced three other religions: Hinduism for ten years, Buddhism for ten years, and Islam for ten years. Nobody else has ever done that.”
For a brief biography, I recommend Barry Boyce’s story “Fifty Years on the Razor’s Edge” from the November 2009 issue of Shambhala Sun.
This was a man who befriended Huxley and the Dalai Lama, who studied Zen and practiced Sufism and dropped acid with Leary. I certainly don’t agree with everything he wrote — he primarily identified as a Christian, after all — but if you’re the sort of cross-path seeker who would read my blog, the odds are excellent that his life’s work indirectly affected you in some way.