An entertaining, interesting and unsettling visualization of major battles between 1000 and 2008, AD, especially around the video's climax (1930s Europe, naturally).
Seeing millions upon millions of deaths reduced to exploding pixels and set to a bit of Wagner has a way of triggering a sense of foggy detachment from the horrors of war. At the same time, one can't help but wonder what a video of the next millenium will look like.
If you find this thought experiment frightening or unnerving, some words from Carl Sagan may serve as a comforting dose of optimism. Though he once lamented that humans are a species "riven with rivalries and hatreds" and incapable of "[putting] our own planetary home in order," Sagan also believed that our potential for progress would ultimately win out.