kctipton writes "LATimes.com (free registration required) had a huge and well researched two-part story over the weekend about a plane crash in the 1950s that was treated as a top secret national security concern just because the US government wanted to say it was. The daughter of one of the victims in the crash never did get close to the full truth until she started digging around on the internet. Serendipity also played a part in her success.
The link above is to the second part. There's a link on that page to the first. Read them in either order. It's fascinating."