I wish people cared more about money that was spent effectively, and less about money that was given to a charity. It's not enough to just spend money on charity, as Givewell.net notes:
Conventionally, most people expect that charities are
probably accomplishing good unless there's proof that
money is being misappropriated. We disagree: we think
that charities can easily fail to have impact, even when
they're doing exactly what they say they are.
Microcredit is still an unproven intervention. It seems like an obviously good thing, but we have a paucity of evidence for its efficacy as a remedy for poverty. The best available randomised trials show indifferent results, with only marginally statistically significant benefits.
While a new search engine or email reinvention sounds daunting but lucrative, in my opinion the most impactful "frighteningly ambitious startup ideas" are like Kiva'.
