Information gleaned from social networking sites has been successfully used as evidence for criminal investigations.

This was the first time I attended this fabulous annual conference held each July in Seattle.  Here's an overview.

For obvious reasons, not much is written about what Federal Air Marshals do, but here are a few interesting articles that might be insightful.

TSA has revealed some 2008 security protocols - it might be of interest if your story involves an airport and you want believable security scenarios, or even if you just travel a lot and are curious!