I used to think that I needed my organs, that I wouldn't be complete in reincarnation if some of my organs were donated (I used to wonder if people who live today with certain organ failures were people who donated organs or had organs damaged in their past life...).

I read a story about an ancient statue of a Buddha being destroyed in Tibet, and some of the monks being outraged and upset, and someone reminded them of non-permanance and non-attachment, two very important concepts in Buddhism, and that while you have attachment to something physical (the Buddha statue... or your body's organs) you are being held back in your spiritual journey to enlightenment. I also like to remember that the Buddha taught compassion and kindness, and love for everyone like they were your own family. If you were on your deathbed, knowing you were definately going to die for some reason, and one of your family members would be able to live a full and happy life if you donated one of your organs to them, would you choose to donate them? I would, and so loving everyone like they were family means I will donate my organs so that someone can live and hopefully practice the same love and kindness to others.

That said, I defiantely don't judge anyone for not donating... I really only recently deided that is something I want to do, and know exactly what its like to be uncertain and not want to donate.