Please note that this list of resources is not exhaustive.

University of Minnesota Human Rights Library.
Comprehensive site includes Decisions and Reports of U.N. Human Rights Committee and of other U.N. Human Rights bodies, Treaties, Inter-American Human Rights System.
Amnesty International.
Annual reports on various countries; Links to related sites.
Asian Human Rights Commission.

Human Rights Internet (HRI)
  Network of human rights organizations including documents and guides
Human Rights Watch.
Coverage of breaking news, World Report and Country Reports (under Publications).
Genocide Watch.
Site contains both international instruments and domestic legislation of many countries against genocide.
Prevent Genocide International.
News and Educational Material. Very good for national legislation on genocide.
Netherlands Institute for Human Rights
The "Library" section provides texts of some human rights instruments and information regarding their ratification; the "Case Law" section gives cases from international criminal tribunals and decisions from UN human rights treaty bodies, from the Utrecht School of Law.
International Committee of the Red Cross (ICRC)
Texts and commentaries on the four Geneva Conventions; Many other treaties; Basic rules of humanitarian law in armed conflict.
United Nations Research Guide: Human Rights.
Good explanation of functions of various U.N. human rights bodies and links to them.
U.S. Dept. of State Country Reports.
Annnual reports on human rights in many countries.