Organizations that help those with unwanted same-sex attractions overcome homosexuality

Religious based:

Exodus International - the largest Christian resource
Guide to Exodus affiliates across the United States and Canada
Exodus global alliance across the world
Homosexuals Anonymous - Fellowship Services – Christian 14 step program
Homosexuals Anonymous chapters across the United States and world
Courage – a resource for Catholics
Courage chapters in the United States
Courage chapters across the world
Evergreen International - a resource for Latter-day Saints
Jews Offering New Alternatives to Homosexuals (JONAH) – Jewish based ministry
Parents and Friends of Ex-Gays and Gays (PFOX) – support for families and an ex-gay advocate organization

Professional based:

National Association for Research & Therapy of Homosexuality (NARTH) - A professional organization whose primary goal is to make effective psychological therapy available to all homosexual men and women who seek change.
American College of Pediatricians – A professional organization dedicated to the health and well-being of children.
Warren Throckmorton, Ph. – Researcher of homosexuality and changing sexual orientation