I put this info up in a thread in Non-US Electrical Systems & Trades but thought others would enjoy it.
I am sure any "Sparkys" would enjoy a visit to The Boston Museum of Science Theater of Electricity They have Tesla coil demonstrations and the world's largest air-insulated Van de Graaff generator.
Indoor lightning is cool I have been there a few times. In the picture you can see a guy in the lower cage demonstrating the "Faraday Cage" these are some of the smaller sparks seen during the show many are 10 to 15 feet (3 to 5 meters)
Here is a link to take you to their site, I highly recomend a visit if you come to Boston http://mos.org/sln/toe/