OK - for the most part I agree, it's not fair to animals and after all - we wouldn't potentially harmful drugs and so forth tested on us, so why do it to something that doesnt have a voice to say "no"?
Buuut.... There are certain drugs and treatments (such as cancer cures/treatments and other fatal illnesses) that cannot be tested on humans as the reactions to the would be both unknown and possibly lethal. So testing these drugs (which would better humanity in the long run) on an animal that is as close to a human as possible and noting the reaction is the best way to find out how well a certain drug/treatment works.
I do not agree in any way shape or form with the testing of cosmetics on animals. It is cruelty in the most severe degree and utterly pointless. An animal has no use for cosmetics, so why not test them on a subject that would benefit from the use?