In Memory of Aaron Swartz
blog.givewell.org
blog.givewell.org
For an example of their work, an analysis of the value of giving cash directly to those in need (instead of, say, a cow): http://blog.givewell.org/2012/12/26/the-case-for-cash-2/
Their top recommended charities: http://www.givewell.org/charities/top-charities
(Fwiw: before I entered tech I was a consultant helping big foundations (like Gates, Packard, etc.) assess their performance (as part of http://www.effectivephilanthropy.org). So for a tech person I consider myself reasonably well-versed in nonprofit evaluation--and how difficult it is.)