Make the donor special
By making the donor special (either feeling special och actually being special) might increase the amount of donors.
If I were to know that I actually would make a difference, would I help more then? I think that by making the future donors feeling special in some way would increase the number of registered donors.
There is some much information everywhere around us, all day long, so we read up on things we consider easy or fun to not be "bothered" with difficult stuff (think about paparazzi-magazines or reality shows people seems to be addicted to). The information to reach people has to be simple, easy and delivered in quite a short period of time to catch our attention.
But if there could be a way of making the donor feelin special, that they could make a different, would that mean more donors? "You, yes just YOU make a difference!" For me, a number of the difference I would make, would make me feel proud and maybe would I either with that feeling (or guilt of being on the way of not going) help out more in the society. What if you knew that by going to the blood bank you help 0.00xxx people to live longer? What if you knew you you saved 0.00000x peoples lives? Would that be amazing, no matter how small the number is, YOU make a difference!