The Yogyakarta Principles are a key document in international human rights law, which are intended to provide a framework within which to apply LGBT rights to existing international law as put forth in the Universal Declaration of Human Rights; in effect, the closest thing to an international Bill of Rights the world's gay and transgender community has. Signed by 29 legal and human rights experts in November of 2006 (at a conference in Yogyakarta, Indonesia, from whence the name), the principles themselves lack the force of international law, but are intended to affirm the specific application of codified human rights to LGBT people. In addition, the principles include a number of recommendations to states and NGOs, including the UN, on implementation.
The document itself is legalistic; it seems unlikely, after all, that anyone's going to stand up in a legislature and say, "Give me a pluralistic approach which recognises and affirms the interrelatedness and indivisibility of all aspects of human identity, including sexual orientation and gender identity, or give me death". But this being a world in which homosexuality is illegal in 76 countries, and carries the death penalty in 5, it seems reasonable to conclude that if human beings have certain inalienable rights, not being killed on the basis of sexual identity should be one of them, and that someone probably ought to be writing it down.
The rights it sets out are fairly intuitive; the right to equality before the law without discrimination; the right not to be executed, attacked or harassed due to sexual orientation; an equal right to privacy, work, education and housing; and the rights of free speech and assembly.
More to the point, it was the Yogyakarta Principles that ultimately informed a UN declaration on LGBT rights proposed in 2008, which at time of writing has been signed by 68 of 192 member countries. That bill remains in limbo, having been more or less ground to a halt by a rather cool reception from Russia and China, not to mention a counter-declaration that said that it could end with 'the social normalization, and possibly the legitimization, of many deplorable acts including pedophilia.' If that doesn't sound repellent enough on the face of it, it may be worth noting that the bill in opposition was sponsored by such leading lights of equality and justice as Zimbabwe, (Gaddafi) Libya, (Mubarak) Egypt, Iran, Saudi Arabia and North Korea. For an extra dose of irony, some of the most vocal support came from the Vatican, which, cheap jokes notwithstanding, is a state that within its borders until comparatively recently had an age of consent of 12*.
Heinous lies aside, however, the Yogyakarta Principles have more or less become the de facto basis in international law for LGBT rights amongst many of the countries that signed the UN declaration; almost the entirety of western Europe, most of the Americas, Australasia, as well as Japan. The US itself had initially opposed it, under the Bush administration (in fact, the only western state to have done so), a decision which was reversed under Obama. As it stands, the original declaration has 68 countries behind it, the counter-declaration 57, which leaves the General Assembly more or less deadlocked.
It might be argued that the Principles themselves haven't succeeded in doing much beyond making a lot of westerners feel good, but the fact remains that bringing sexual orientation and gender identity into the view of human rights activists was and remains necessary, and is a vital step towards reaffirming the primacy of Article 1 of the Universal Declaration of Human Rights, namely that:
All human beings are born free and equal in dignity and rights.
The full text of the Yogyakarta Principles is available in PDF form in English here, and is also reproduced in each of the UN languages.
* It's currently 14, which isn't much better, but at least matches the Italian law.