I used to do it regularly, but I can't anymore.
I used to donate blood every three months. I did this for around 3 years I think. Then, I can't remember what year it was, 1999 or 2000, I think, when Canadian blood services implemented a rule that you can't give blood if you lived for 3 months or more in the UK during a certain time period. I did my masters degree in the UK and lived there for 10 months. I would send Dave as my proxy, and let them tap his veins but he also lived in the UK for 5 months for a work placement. So it totally sucks that neither of us are eligible.
I'm a very squeamish person in general, but I really felt like blood donation was something everyone who could should do, even if it's just once ever. I would come out of the clinic and feel great and slightly superior to the people I passed on the street. "I saved a life today, what have YOU done?".
In Canada, it's really easy to donate, you set up an appointment at one of the 41 permanent collection sites that the Canadian Blood Services operates. Before you do that it's a good idea to see if you are eligible to donate here. There is also a page that gives you an idea of what to expect. It barely hurts when they put the needle in and from there you just wait for your bag to fill. I was always on the slow side, some of the bigger guys would be done in like 20 minutes. From start to finish, including questionnaire, hemoglobin check and donation, we're talking about an hour. AND they give you cookies and a sugary drink like Tang afterwards. YUM! I'm not sure what the procedure is in the US but you can find the information here.
During my dad's surgery, he needed 2 units of blood and he needed another 2 units while he was in the ICU. I'm very grateful to all the people who made those donations which helped save my father's life. And I like to think that the donations that I made in the past helped to save someone else's parent or child or grandparent or friend.
Leave me a message if you have any questions. It's been a while since I've been able to do it, but I'll try and find you the answer if I don't know it.