I recently donated blood. I am sad to say that donating blood is not something I commonly do. It is important that people donate blood since many people need blood and there is not a good substitute for it. There is almost always a shortage of blood available. I have never needed a blood transfusion but many people do need them. If I ever do need a blood transfusion, I would hope that other people have donated blood. I do not have a good excuse for not giving blood. I am healthy enough to give blood and do not have a fear of needles (Trypanophobia). The reason I don't give blood often is mostly laziness. I will make an attempt to give blood more frequently in the future.
In the United States you can give blood every 56 days. In Japan you can give blood a maximum of three times a year and there has to be a three month period between the times you give blood.
More information about donating blood in the United States can be found at: GiveLife.org It also has some interesting games like Blood Trivia which is a Jeopardy type game about blood.
I have found on the web a blog in which a foreigner to Japan tells about his giving blood in Japan and that can be found here: Rejected from Donating Blood