Family and Partner Support:
Straight Spouse Network: has a UK branch, supports straight partners of LGBT people (mainly partners of gay or bi men, but does point to some trans-appropriate resources).
Support for (primarily) trans people:TransFamily (Cleveland, USA): US support network for trans people but also has several mailing lists for partners and family.
Mermaids: UK organisation for young trans people and their families, with support and resources for both.
Press For Change : lobbying and legal organisation supporting trans people in the UK. Resources mainly relate to relevant law, also has extensive list of trans organisations.
Transsexual-UK: Yahoo group for trans people, familes and friends.
The Gender Identity Development Service: gender identity clinic for young trans people with resources and support for them and their families, including guidance for schools.
Gendered Intelligence: organisation providing support and resources in gender diversity issues especially for young people, has resources and events aimed at families
Research and training in trans issues:
Gires (Gender Identity Research and Education Society): support and research organisation for trans people, with resources and access to relevant research including material for schools and employers.