Loving Kindness 

Theory

The Buddha's words on Loving Kindness called the Metta Sutta

Training the Mind and Cultivating Loving Kindness  

Practical

Kindness Meditation Practice

BuddhaNet's Loving Kindness Meditation

Atisha's Tibetan Meditation of Loving Kindness

Loving Kindness by Shinzen Young

Unlimitedloveinstitute.org  The Institute for Research on Unlimited Love