Peak Oil. This is something we've all heard about to one degree or another, and here is a site that does a pretty good job bringing lots of information together into an easy overview.
The author takes a pretty pessimistic look, but on the other hand, he does quote quite a few people in the Bush administration spouting an equally pessimistic look. In other words, even if you don't buy all the worst-cases on this site, they still are playing (or will play) a large role in world politics (whether the powers that be truly believe it all or just say they do).
Personally, I expect some bad shit to go down, but not quite as bad as outlined here. However, if we've got Bush&cohorts holding the reins as all this develops, I think my homeland has got a great shot at fascism...