My favorite conspiracy theory on Tunguska: http://www.reformation.org/tesla-and-tunguska.html
People love to make up a lot of theories and conspiracies, it's nothing new.
What is particularly worrisome is that Tesla was a very brillant man and that he believed himself to have caused this. From the information that we have, it wasn't a marketing stunt by his entourage. The guy himself was working on this particle-beam for some time and claimed to have triggered it that night. He tried to sell the technology for more almost 3 decades.
Was this made up, was this a coincidence, or did it actually happen?
It's been over 100 years and no one is certain.