GENDER.ORG (http://www.gender.org)
National Center for Transgender Equality (http://nctequality.org/)
Remembering Our Dead (http://www.rememberingourdead.org/)
Transgender Health (http://trans-health.tgforum.com/)
Transgender Law and Policy Institute (http://www.transgenderlaw.org/)
International Foundation for Gender Education (IFGE) is a great site (http://www.ifge.org)