People for the Ethical Treatment of Animals (PETA) - PETA's animal rights campaigns include ending fur and leather use, meat and dairy consumption, fishing, hunting, trapping, factory farming, circuses, bull fighting...
RSPCA - Since 1824, their vision has been "to work for a world in which all humans respect and live in harmony with all other members of the animal kingdom."
CMF - an article on Animal Experimentation from the Christian Medical Fellowship