Suggested Readings for Beginners

Buddha: A Very Short Introduction by Michael Carrithers
Buddhism: A Very Short Introduction by Damien Keown
Buddhism Without Beliefs by Stephen Batchelor
Mindfulness in Plain English by Bhante Gunaratana
What the Buddha Taught by Walpola Rahula
Tibetan Buddhism from the Ground Up by B. Alan Wallace
A Flash of Lightening in the Dark of Night by HH the Dalai Lama
The Tibetan Book of Living and Dying by Sogyal Rinpoche
Enlightened Journey: Buddhist Practice as Daily Life by Tulku Thondop
Path to Buddhahood: Teachings on Gampopa's Jewel Ornament of Liberation by Ringu Tulku

For more in depth reading:

The Words of My Perfect Teacher by Patrul Rinpoche
The Way of the Bodhisattva by Shantideva - Translation of the Bodhicharyavatara by the Padmakara Translation Group
Introduction to Tantra: the Transformation of Desire by Lama Yeshe - edited by Jonathan Landaw
Dzogchen: The Heart Essence of the Great Perfection by HH the Dalai Lama