I am very cross with the Blood Donor service, I havent been able to donate for a couple of years as have been pregnant or breastfeeding and they wouldn't take it, but I asked for them to take a sample for bone marrow testing and they refused!
It's only a small amount they need!
And I had my 'I've given shedloads of blood, aren't I a hero' coloured card when I moved to Wales, and they took it away and replaced it with a bilingual one, so it looked like I hadn't donated any !
We used to give blood as a house in uni, shamefully normally when we were broke as you got free bics and drinks and you could get drunk faster afterwards....but it meant all my housemates now give regularly so I don't suppose the reason matters!