Yesterday I've made my 38th blood donation. I can heartily recommend it to (almost) everyone. Especially if you are a "simple" full blood donor, it will take at most half an hour, a couple of times a year, at a moment you choose within a two-week interval. Oh, it doesn't really hurt and you get free coffee and sandwiches. If you're in the Netherlands, you can
register on line. I think it's an easy way to do some good for society.
I'm not a full blood but a plasma donor myself. I have the most rare blood type (AB), which means I can receive all other types but my blood can only be given to the 3% of the population that also has AB. That makes it not quite useful for donation, but it is useful to make medicine out of. During the donation the blood is filtered and only the plasma is kept, all other parts are pumped back into my circulation. This allows for a larger volume of plasma to be donated at a time, but has as a drawback that it needs an appointment and takes longer.
The most commonly asked question is whether you get paid. You're not. The reasoning is that this could motivate people to be a bit too positive about their health situation when they need money, and thus could hold back relevant risk information. The selection procedure depends on a reduction of chances. This also leads to homosexuals being completely excluded from donations. While sound from a purely statistical reasoning, it is debatable whether this is fair on an individual level.