I recall vividly when I was a little girl and my father would come home from a hard day's work sporting that little round red button which read, "Be nice to me..... I gave blood today". Remember them? Those were the days where all you got for your precious pint was that button, a feeling of satisfaction in doing a good deed, and the unwavering admiration from a daughter who thought her father hung the moon.
Nowadays we've gotten t-shirts (Sloane Kettering), coupons for ice cream and this coming Monday night in my neighborhood they'll be offering Starbucks gift cards. I guess lately people need more of a push to be altruistic.
But whatever your motivation, giving blood is a tremendous mitzvah and I encourage everybody to donate in their neighborhood (call your local Red Cross if you don't know where).