Bitcoin hoarding for charity: Buy some amount of bitcoin, and keep it in a series of of wallets dedicated to various causes. Precommit to hoarding all of the amounts for a significant time, but spend the ones with the most warm-fuzzy results the soonest because that results in pumping up the value of bitcoin.
Eventually, at a point where the value cannot be pumped further by expending more on warm-fuzzies, spend hoarded amounts on utilitarian-optimal causes in a way that leverages economies of scale to achieve maximum impact.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.