Are you kidding me? Encarta was the bomb. As a kid, in the days before the computer was an endless source of information and distraction, I would just browse Encarta and learn random stuff.

Once some kid in my third grade class asked why race cars made noise they do when they passed, the teacher didn't give a satisfactory answer, and I was able to explain the Doppler effect to them based on animation I watched on Encarta.

Good stuff.