Here is a thought for the 'things will soon get better cause this is all cyclical' croud.
A large part of the US and global economy is driven by population growth.
More humans mean more housing, more food, expanded road projects, increased consumption, etc, etc.
This is a game we can't play forever and according to some of the best estimates the world is quicly approaching its maximum sustainable population. Some estimates put this number somewhere around 10 billion people, and at current growth rates many of us will see that number in our lifetimes.
http://www.census.gov/prod/2004pubs/wp02-1.pdf
Unless the world wises up and starts instituting some sort of large scale population control policies (which is unlikely since this growth is worth billions and people don't like being told what to do) we are likely to surpass this limit causing some cyclical activity that would best be referred to as calamity and war.