In case you're not already aware of the Hubbert Peak AKA Peak Oil from other sources, it's simply the application of the law of diminishing returns towards oil extraction. Now, in case you're wondering "What does this have to do with anything?", it appears that global oil production is set to peak any time now (no more than a few years from now), after which acquiring oil becomes a zero-sum and then a negative-sum game.
With demand already outnumbering supply before that (think of China and India), predicted events range from (permanent) recession, depression, a massive die-off, global (nuclear) war for resources, a return to a pre-industrial age and even outright human extinction or, if you're more optimistic, a technological breakthrough to continue the American Way of Life (tm) because of the huge incentive.
Keeping Peak Oil in mind does put an interesting perspective on the events that happened the past few years, don't you think?
Oh yeah, before you start going on an ad-hominem spree towards the proponents of this theory, remember that they come from all over the political spectrum.
For one particularly pessimistic outline, try http://lifeaftertheoilcrash.net/
Here are some other great links on this issue. This will be the definitive geopolitical force in our life-times. This is the century of the scramble for control of the remaining oil reserves. It goes way beyond cheap gas and cheap plane flights, it goes straight to war, starvation, economic recession, possibly even the extinction of homo sapiensif we can not adapt to a more simplistic existence.
http://www.fromthewilderness.com/free/ww3/040403_oil_war_bbc.htmlhttp://www.fromthewilderness.com/free/ww3/102302_campbell.htmlhttp://www.fromthewilderness.com/free/ww3/013004_in_your_face.htmlfreedomburns
