Interights
Much useful information on litigation, including, particularly, Manuals for Lawyers on the European Convention on Human Rights

Press for Change
Their website contains much valuable information about trans issues and about the campaigns for change in the UK.

The International Commission of Jurists
See especially:

• Practitioners Guide No. 4 – Sexual Orientation, Gender Identity and International Human Rights Law
• Sexual Orientation and Gender Identity in Human Rights Law, References to Jurisprudence and Doctrine of the United Nations Human Rights System

Council of Europe site for Human Rights Education for Legal Professionals
This site provides materials and tools for education on the European Convention on Human Rights (ECHR). Has some useful basic training tools, and more advanced materials.

European Commission on sexual orientation law - ECSOL
Network of lawyers working on sexual orientation issues. Has news, information on current cases, and links to useful documents.

Press service of the European Court of Human Rights
In a bid to make its case law more accessible, the European Court of Human Rights is publishing fact sheets on case law associated with a number of topics, including "homosexual rights", " homosexuality: criminal aspects", and “transsexuals’ rights”. However, you should be aware that, for the non-expert, these fact sheets can be confusing because they include quite a number of negative judgments which have now been overruled by the Court, but without making this clear.
Find the fact sheets produced by the Press Service here.