There are some ideas that are so simple and so effective. Take Nets for Life, for example. They provide nets soaked in insect repellent to people in Africa in an attempt to curb malaria. According to their website, around 655,000 people die each year from malaria, with most of those victims being kids under 5.
Check out their website and donate if you can: http://www.netsforlifeafrica.org