Many books have been very meaningful to me.
The older ya get, the more important books there can be.
Following are a list of books about spirituality, social science, philosophy, and science fiction that have been important to me.
Key books on integral spirituality, most recently important to me:
Integral Psychology by Ken Wilber
Anything else by Wilber. The best summary of this work is by Wilber himself, available online: Outline of An Integral Psychology. Or: Waves, Streams, States, and Self--A Summary of My Psychological Model.
http://wilber.shambhala.com/html/books/psych_model/psych_model1.cfm/
The Crystal and the Way of Light by Namkhai Norbu
Dzogchen is the innermost yoga of the Nyingmapa lineage of vajrayana Buddhism, where the direct experience of nondual freedom is the path. Norbu Rinpoche is a gifted scholar and teacher, skilled at explanation and at inviting people to be liberated in their experience. There are a number of books on Dzogchen by realized lamas. This is a very good one.
Luminous Night's Journey, by A.H. Almaas
This is one of the richest accounts I have read of a journey in enlightenment. The book evokes, for the reader, a feeling for the experience of enlightenment as it unfolds. Almaas founded the Diamond Approach, which is a wonderful synthesis of western depth psychology and Sufi, Gurdjieff, Tibetan Buddhist and other teachings. I am not currently doing this work, but I find the ideas very helpful. Here is an introductory passage from the book, online: http://ridhwan.org/lnj_intr.html
"Elixir of Enlightenment" by A.H. Almaas
This is the best essay I've read on spiritual teacher-student relationships. The essay is especially helpful on an important type of problem in spiritual relationships. In a nutshell, there a number of archetypal spiritual qualities or essences. Most spiritual teachers only manifest one or a few of these qualities. Skilled teachers know how to direct students to people with whom they need to work. Other important books by Almaas are: The Void, the Diamond Heart series.
Other key books on spirituality in last 25 years:
The Bhagavad Gita
The Gita is rich in essential teachings about different types of yogic paths: karma, bhakti, jnana, meditative yoga, etc. Been reading this since 1980. Also enduring rich resources for inspiration and contemplation and insight for me are: Patanjali's Yoga sutras, Narada's bhakti sutras and the Srimad Bhagavatam.
Tao Te Ching, translation by Stephen Mitchell
I really like Mitchell's translation. Read this over and over during a time when Qi gong in mid-90s.
Zen in America, by Helen Tworkov
I converted to Mahayana Buddhism in 1990 based in part on the tales in this book. Tworkov writes about the adapting and expression of Buddhist teachings in western social contexts and processes.
Autobiography of a Yogi, by Paramahamsa Yogananda
This inspired me deeply when I read it around 1983. I decided to study Kriya yoga of Yogananda at the time and eventually was initiated into the system.
The Seth Material, by Jane Roberts
This book opened up possibility of exploring spiritual reality through direct experience. Read this around 1977. Roberts later books offer various explorations of and teachings about consciousness realms and phenomena. Roberts aspect psychology (across time, simultaneous, multi-life incarnation processes and developments) is a necessary topic of study as an alternative and perhaps corrective to traditional western and eastern metaphysics.
Others:
The Magic of Findhorn, by Paul Hawken
Ishmael, Daniel Quinn
And dozens more.
Some key social science and philosophy texts:
Alternative Modernities; Transforming Technology, by Andrew Feenberg
Monopoly Capital, by Harry Braverman
CyberMarx, by Nick Dyer-Witheford
From Margin to Center, by Bell Hooks
Science in Action, by Bruno Latour
The Philosophy of Social Ecology, by Murray Bookchin
A People's History of the United States, Howard Zinn
No Logo, Naomi Klein
Social Construction of Reality, by Berger and Luckmann
The End of Work, Jeremy Rifkin
Communities Directory: A Guide to Intentional Communities and Cooperative Living
Green Politics, Charlene Spretnak and Fritjof Capra
The Monkey Wrench Gang, Edward Abbey
Postmodern theory series, by Stephen Best and Doug Kellner
One Dimensional Man, Marcuse
Dialectic of Enlightenment, Adorno & Horkheimer
Philosophical Investigations, Wittgenstein
Meditations, Descartes
Favorite science fiction works.
Science fiction was my first love and has shaped my multi-dimensional view of reality.
For ten of my favorite writers, I made brief summaries of works and website link. A number of this works shaped the way I see the world and/or my hopes and imaginings about our future:
Ursula K. Le Guin, Left Hand of Darkness; Earthsea series; The Dispossessed
Leguin weaves beautiful worlds. Her soft scifi is good fiction, period. The ambi-sexuality (persons able to be either sex based on hormones floating in air) in Left Hand of Darkness was formative in my wide-open gender concept in mid teens. The early books in Earthsea series are quite magical; the stories drag on a bit as series goes along. The anarchic society portrayed in The Dispossessed informed my political ideals.
http://www.ursulakleguin.com/
Greg Egan, Diaspora
Brilliant, hard scifi: starts with development of an AI and then a cosmic AI romp. Best to read this for ideas more than for coherence as many sub-plots/ideas go off in various directions. Some think his Permutation City, a story about a code copy of a person trying to find way back to a body, is his best novel. But, I love cosmic AI.
http://gregegan.customer.netspace.net.au/
William Gibson, Neuromancer series
Classic cyberpunk and very good fiction: techno-scientific intrigue, advanced AIs, gritty realism. http://www.williamgibsonbooks.com/
Kim Stanley Robinson
Red Mars; Green Mars; and Blue Mars
Best multi-dimensional near future hard sci-fi that I've read. Looks at development of human society on Mars and in solar system in geological, biological, political, and various social domains. Ponderous at first and at times, but great integral extrapolations.
http://www.sfsite.com/lists/ksr.htm
J.R.R. Tolkien, Lord of the Rings trilogy; The Hobbit
Grand fantasy and myth making. http://www.tolkiensociety.org ; http://www.tolkien-archives.com
Robert Heinlein, Stranger in a Strange Land; The Moon Is A Harsh Mistress; etc.
Heinlein's best works are inspirations. To grok this, one must read. http://www.wegrokit.com/
http://www.nitrosyncretic.com/rah/srah-archives.html
Neal Stephenson, The Diamond Age; Snow Crash
Stephenson creates zesty, colorful worlds, interlacing virtual reality, social permutations, and edgy science. Action-packed. http://www.nealstephenson.com/ ; http://www.well.com/user/neal/
Zenna Henderson, pilgrimage: The Book of the People; Holding Wonder; etc.
Well spun tales of human-like species with psi powers trying to blend into human society. http://www.adherents.com/lit/bk_Zenna.html
Kate Wilhelm, Where Late the Sweet Birds Sang
Lyrical read. Small groups of human clones are raised to repopulate a world once destroyed. http://www.hycyber.com/SF/wilhelm_kate.html
Robert Silverberg, Son of Man; the Stochastic Man
Psychedelic sci-fi. I like his 70s novels best. http://www.majipoor.com/
I made a list of my favorite 60 authors, but will skip including that. For more science fiction reading ideas, see...
This site lists award wining science fiction works:
http://www.dpsinfo.com/awardweb/
Best reads of the year at SF Site:
http://www.sfsite.com/columns/best04.htm
See bottom of page for previous years.
These sites have lists of best sci-fi works:
http://www.geocities.com/Area51/Cavern/6113/top100.html (based on votes by over 3000 people)
http://home.austarnet.com.au/petersykes/topscifi/ (various lists)
http://www.strangewords.com/weirdbooks/scifi100.html
http://www.artsforge.com/film/scifi.html
Gardner Dozois, Editor of Asimov's Science Fiction magazine, has been editing the Year's Best Science Fiction annual collections for many years. Each volume has an introduction with a review the year's best science fiction.