Poynter's Roy Peter Clark took the long suicide note of the guy who flew his plane into the IRS building in Texas and did a full-blown analysis of the language.
I've never seen this done, and, although it's a critique done at arm's length -- Clark obviously didn't know the pilot, etc. -- it does show that the choices people make when they write can tell significant things about them.
One of the most intriguing, perhaps chilling, things in Clark's analysis is his note that a lot of the writer's phrases are heard every day from politicians and commentators from both sides of the political spectrum. It makes me wonder: Are those people reflecting current thinking in America, and are we living with hundreds of thousands of people who really believe what the pilot believed? Or did the pilot, having listened to that language again and again and again, use it to polish his disenchantment with his perceived enemies?
And lastly: Be sure to read the comments. There is a really interesting discussion going on, reactions to Clark's piece, some people saying Clark never should have written it, and Clark has responded a couple times.