Philippine tarsiers, the wolrd's smallest primate, are on the edge of endangerement in the Phillippines due to deforestation and illegal trade in exotic animals.
This small, but successful sanctuary is the only place you can see them in their natural habitat. There are other "conservation" locations in the area, but they are essentially zoos.
Tarsiers become depressed in enclosed spaces. They have even been known to commit suicide. In fact, a tarsier, which is small enough to fit in the palm of your hand, need a hectare of space to itself as it is primarily a solitary animal. They are nocturnal as well - their eyes are 150 times bigger than a humans in scale to the body.
Your visit to this sanctuary helps support its efforts and helps spread education. At only 60PHP (they really shoudl charge more) its worth it. The tarsiers are SO DARN CUTE!