A reminder for everyone: on this day in 1983, Stanislav Petrov saved the world.
It occurs to me this time around that there's an interesting relationship here - 9/26 is forgotten, while 9/11 is remembered. Do something charitable, and not patriotic, sometime today.
As Richard Kenneway has pointed out, it looks like you're ignoring the effects on the 99% who would die.
Also, all of the positive effects of others' deaths you're pointing out should scale. If the death of billions would reduce potential water shortages by a lot, then the death of one should reduce them by a little. The same seems true for space, other resources, war, and global warming.
Do you think the cost/benefit situation of a single death is similarly ambiguous?
See my answer here: http://lesswrong.com/lw/7t7/stanislav_petrov_day/4wt5