Loving Kindness
Theory
The Buddha's words on Loving Kindness called the Metta Sutta -
Training the Mind and Cultivating Loving Kindness
Practical
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