See Nate's comment above:

http://lesswrong.com/lw/n39/why_cfar_the_view_from_2015/cz99

And, FWIW, I would also consider anything that spends less than $100k causing a small number of top-caliber researchers to become full-time AI safety researchers to be extremely "effective".

[This is in fact a surprisingly difficult problem to solve. Aside from personal experience seeing the difficulty of causing people to become safety researchers, I have also been told by some rich, successful AI companies earnestly trying to set up safety research divisions (yay!) that they are unable to hire appropriately skilled people to work full-time on safety.]