RED is an app that makes it easier for you to save a life, donating one unit of your blood will help saving 3 lives.
RED will tell you about those who need blood in your area, and will order them to maximize the utility, so you can donate for those who really in need to blood.
RED will also let you request blood whenever you need it, just click "I NEED BLOOD!" and fill the form in 30 sec, and just wait for donors.