GLSEN, the Gay, Lesbian and Straight Education Network, is the leading national (United States) education organization focused on ensuring safe schools for all students. Established in 1990, GLSEN envisions a world in which every child learns to respect and accept all people, regardless of sexual orientation or gender identity/expression. GLSEN seeks to develop school climates where difference is valued for the positive contribution it makes to creating a more vibrant and diverse community.
 
http://www.glsen.org/cgi-bin/iowa/all/home/index.html

Pride Education Network ? formally GALE BC. A group of lesbian, gay and bisexual educators, and supportive colleagues, based out of British Columbia. Includes various resources and publications.
 
http://www.pridenet.ca

Gay Straight Alliance Network - Group that connects the California Gay/Straight Alliances to each other and community resources. Includes a directory and guide for starting a school group. Also aims to empower young activists to fight homophobia and transphobia in schools.
 
http://gsanetwork.org/