I can understand the desire to make sure your money goes towards actual programs instead of overhead, but MSF - at least in the US - is one of the better big name charities I can think of on that front.

http://www.charitynavigator.org/index.cfm?bay=search.summary...

86% for program costs. Wellbody is at 95%, but they don't have any salaries or employee benefits listed, among other things that inevitably gobble up some small percentage of money for bigger charities.