Most people, the vast majority in fact, do not give blood, but millions do. I do, about 3-4 time per year.
Like most, I give at a local Red Cross office or when the blood mobile comes to my church or work.
Similar to a holiday like Christmas and Halloween, donations happen routinely, broadly and predictably.
Seems like a marketing opportunity and I am not talking about the companies/brands that supply the free drinks, and snacks donors are asked to consume at the conclusion of the donation.
What would get a blood donor's attention? What frame of mine are they in after they give blood? How could you serve these folks? Could you meld these folks into a community that takes action to a certain objective or activity - a community of people that are passionate about something (doesn't have to be blood donation), who would interact routinely?
O.D.O.o.O.D.B.