Upvoted because I never gave blood and then I lost the ability to give blood. This frustrates me, and is one of my few, real, life regrets. Thanks for doing your part.

This has reminded me to arrange to give blood. Thank you.

Some things I just remembered: You can also donate blood plasma, sign up as a marrow donor and in case you do not want to go through with cryonics you can sign up as an organ donor. Your marrow is especialy valuable if your genetic makeup differs from the majority population.

Another procrastinator here. I gave blood before but fainted once before and felt uncomfortable all other times. I'll try and give blood again soon to see if that issue cleared up.

I also give blood once a year. It's one of those winwin cases where there is a benefit for oneself as well as for others:

Blood donation

The studies related to this have some methodological issues but overall the effect size is so large, and the cost and risks so low, that it is worth inclusion. Several studies have indicated that, for men, regular blood donation results in a massive reduction in heart attack.[1][2][3] Other studies have found no such relation.[4] There are also additional health benefits to blood donation.[5] These are just some of the studies on this subject, but on balance after reviewing the evidence, I can say that donating blood once a year is almost certainly worth it if you're a man. Donating too often is probably bad for you though.

http://lesswrong.com/lw/jrt/lifestyle_interventions_to_increase_longevity/