I'd like a quick peer review of some low-hanging fruit in the area of effective altruism.

I see that donating blood is rarely talked about in effective altruism articles; in fact, I've only found one reference to it on Less Wrong.

I am also told by those organizations that want me to donate blood that each donation (one pint) will save "up to three lives". For all I know all sites are parroting information provided by the Red Cross, and of course the Red Cross is highly motivated to exaggerate the benefit of donating blood; "up to three" is probably usually closer to "one" in practice.

But even so, if you can save one life by donating blood, and can donate essentially for free (or nearly so), and can donate up to 6.5 times per year...

...and if the expected ROI for monetary donation is in the thousands of dollars for each life, then giving blood is a great deal.

Am I missing anything?

And as a corollary, should I move my charitable giving to bribing people to donate blood whenever there is a shortage?