There are a number of organizations that greatly support the work of Thich Nhat Hanh and the many monasteries, practice centers and Sanghas around the world. To name a few, these include in alphabetical order,

Center for Mindfulness and Justice
Dharma Teacher Cheri Maples co-founded this organization that offers mindfulness instruction, keynote speaking and organizational consulting and training.
www.mindfulnessandjustice.org

Community of Interbeing: Mindful Living in the UK
http://www.coiuk.org

The Lotus Institute
Dharma Teachers Larry Ward and Peggy Rowe-Ward founded this Institute to offer mindfulness teachings, principles and practices that encourage individual healing and transformation, professional growth, and development in ways that enhance planetary, social evolution.
www.thelotusinstitute.org

The Mindfulness Bell
A journal published three times a year by the Unified Buddhist Church.
www.mindfulnessbell.org

Parallax Press
A non-profit publisher, founded and inspired by Thich Nhat Hanh.
www.parallax.org

Thich Nhat Hanh Foundation
A Foundation that works to continue the mindful teachings and loving practice of Zen Master Thich Nhat Hanh. The funds donated to the Thich Nhat Hanh Foundation benefit the North American monasteries and Plum Village. In addition, financial support is devoted to humanitarian assistance and Dharma education and outreach programs. 
www.thichnhathanhfoundation.org