NOAA
Noaa: Storm Prediction Center: The Online Tornado Faq
What questions do you have about tornadoes? This site addresses, among other things, common safety misconceptions and historic tornadoes, damage facts, and tornado research.
University of Illinois
University of Illinois: Hunt for the Supertwister
Find out how computer generated tornado models are being used to understand the formation of the rare super twisters. You can view a video of the computer model and view the same footage in a slide format which has detailed explanations.
Weather Wiz Kids
Weather Wiz Kids: Tornadoes
This is a great resource for everything tornadoes. Learn things like how they form, how they stop, and when they are most likely to occur. You can also keep an eye on tornadoes in your area.