The Jewel Ornament of Liberation by Gampopa (the Karma Kagyu bible!).
The Torch of Certainty by Jamgon Kongtrul (classic explanatory text on the preliminaries).
The Hundred-Thousand Songs of Milarepa (Milarepa at his finest).
Tantric Treasures: Three Collections of Mystical Verse from Buddhist India (to get a taste of what the early masters Tilopa and Saraha were all about).
With the eye of wisdom we discover a lot of anger in us, any amount of jealousy, resentment, ignorance, desire - mountains of emotion whose existence we would never have suspected in ourselves... We recognize that most of the faults we perceive in others are only the mirror of our own negativity, the reflection of our own disturbed feelings... At the same time, we relieve the world around us of the burden of our own negative judgements."
Gendun Rinpoche Heart Advice from a Mahamudra Master