I learned about the Against Malaria Foundation years ago while researching reputable charitable organizations. I like to do my part by donating to groups that have a much further reach than I, but I don't do so haphazardly. Some organizations are less successful than others, and some only give a proportion of your donation (sometimes a rather small one) to the people you intend to help. Knowing this, I do my homework before hand, and try to make the best choice for the coming month.
To me, AMF is a GREAT choice for giving back, particularly if you do not have a lot to offer. Not only is malaria such a deadly disease, killing hundreds of thousands and sickening millions more annually, but it is SO inexpensive to help save a life! For every $2.00 USD donated (previously $2.50) the organization buys and distributes insecticidal mosquito nets which keep the people from getting bitten by malaria-carrying mosquitoes. The nets also kill the mosquitoes that come in contact with them, decreasing the population of these deadly insects which in turn also decrease the number of deaths caused by them.
And if you are wondering, 100% of donations go to providing nets. Awesome!