There is lots of information on the internet about tornados and hurricanes.
I particularly like this one about tornados with its awesome pictures and interesting facts. Did you know that tornados kill 60 people on average per year? But even in the most notorious area know as "Tornado Alley", the chances of a tornado hitting any particular square mile is only about once in 700 years.
Here are supercomputer simulations of thunder storm and tornadoes.
Here are the NOAA's National Severe Storms Laboratory's(NSSL) Vortex website and tornadoes page.
Here is a cool page on Severe Weather. Also, check out the NOAA Photo Library. It is truly an amazing planet we live on.
This link has instructions for making a vortex exhibit with mist like those seen in museums.
This link is not about vortices per se, but it is about a really neat device that measures humidity in the air using a human hair!