Remember in "It's a Wonderful Life" when they said that every time a bell rings, an angel gets its wings? Well, I've got a better one. Every time you donate enough money for 20 bed nets, a human being doesn't die of malaria.
Each net is about five bucks, so you're getting a hell of a deal. One hundred bucks, and you save a life. Guaranteed. Twenty bucks, and you save, I don't know, a leg.