Snare,
Yes. But considering the number of people who have already read this, the idea of conspiracy theories in general needs to be addressed rationally. Over 240 people have read this OP to this point with only 7 posts to it, which makes it of interest to a lot of people). Lots of nefarious things are done, but light is typically quickly shed on those, at least in the democratic countries. The theories to which I am referring are those identified in the link and the most common: JFK, Roswell, 9/11, etc.
The life cycle of a typical conspiracy theory is well known: how it comes to life and how life is breathed into it. Bush, Cheney and Rumsfield orchestrated and manipulated the U.S. into Iraq, completely without warrant. I don't view that as conspiracy, simply ego and mismanagement, which is why one of the best government servants of the past 50 years - Colin Powell -left the Bush administration and government service. True conspiracy theories vs. the need for secrecy vs. complete mismanagement (and the subsequent coverup). They are very different things.