I think organ and blood donations are the best donations one can give. To donor, they are cheapest thing to donate. They are not hard earned but freely given by Almighty. Blood replaces itself fairly quickly without any additional effort on donor’s part and organs (eyes, liver, kidney, etc.) are practically waste for donor after death. Any use is better than being burned or burried*. Blood donation requires very minimal pain and time and organ donations doesn’t even require that. To recipient, they are gift of life, one of the most valuable gifts anyone can give to anyone else, and way more than valuable than typical sums of money one can manage. It’s like giving your garbage to someone who uses it for their life support system.
For some reasons of sanctity of dead body and various myths prevailing about it, organ donations remain very low, even in advanced countries. Similar rumours float abound for blood donation. I have convinced myself about fallacy of these rumours and decided to donate blood as and when possible. One thing though bugs me, and I am not sure whether it should. In India, donated blood can get spoiled due to improper testing, refrigeration and storage facility and I dread my donated blood flowing down the drains rather than in the veins. I am sure of sanctity of the act and still I somehow love my blood enough to not want it to go waste. Why should that be so? Some part of me says that even though it’s free, my blood is my stuff not to be given up so easily. I think I should take that remote chance for general usefulness of donated blood.
*Zoroastrians (Parsi) of India believe in this thought and hence they dispose their dead bodies by leaving it on "death towers" to feed crows, eagles and other predators. They believe that that's the best use of corpse in feeding to others.