:: Risks to Humanity
In this article we look at some of the most "popularized" methods predicted to
potentially end the world, and assess the probability that the events in
question may actually do just that.
:: 20 Ways the World Could End
This Discovery article by Corey S. Powell (DISCOVER Vol. 21 No. 10, October 2000) lists his opinion of the top 20 ways the world could end. Some of these are pretty far out, but an interesting read nonetheless.