Sure, you knew that the world eradicated smallpox in 1979, but did you know polio has also been eliminated 99% worldwide?
Bill Gates narrates a short talk about vaccines and why they're so important - and also so easy, so cheap, and so obvious as a means to save lives. The talk was animated in a fun way, check it out (it's only 3 minutes long):
The Bill & Melinda Gates Foundation also has a neat interactive infographic on its site, illustrating the fight against malaria, as well. You can see all the progress the world has made, and how much more we still need to do to ensure a healthy life for everyone.