Jon Kabat-Zinn   Full Catastrophe Living  (and many others by him)

Saki Santorelli Heal Thy Self 

Dr Jonty Heaversedge and Ed Halliwell The Mindful Manifesto 

Ed Halliwell How to Live Well by Paying Attention

Vidyamala Burch and Danny Penman Mindfulness for Health: a practical guide to relieving pain, reducing stress and restoring wellbeing.

Mark Williams, John Teasdale, Zindel Segal and Jon Kabat-Zinn The Mindful Way Through Depression 

Mark Williams & Danny Penman Mindfulness: Finding Peace in a Frantic World

Dr Tara Brach Radical Acceptance 

Vidyamala Burch Living Well with Pain and Illness

Eckhart Tolle The Power of Now

Ed Andy Fraser The Healing Power of Meditation

Orsillo & Roemer The Mindful Way through Anxiety

Larry Rosenberg Breath by Breath, the Liberating Practice of Insight Meditation

Leaping Hare press also have a series of short books on mindfulness topics such as Mindful Gardening, Mindfulness and Depression and many more.