I'm a blood and organ donor.
Well technically I donate plasma, since I get a bit of money for plasma. and since I have type AB+ blood, the universal receiver's blood type, i figure my plasma will be more useful than my blood would be anyway.
(For those who didn't know, people with O- blood type can give their blood to anyone, but only receive from the other 6.5% of the population that is also O-, while AB+ people can receive from anyone but only give blood to the 3.5% of the population that is also AB+,)