THE END OF CHEAP OIL By: Colin J. Campbell and Jean H. Laherrère, Scientific American, March 1998
The above article in PDF format
National Geographic article with very comprehensive links.
Colin Campbell's Peak Oil site
Hubbert's Peak This site has links to some very good reading material including M. King Hubberts early documents.
Good discussion of the alternative oil sources that are often touted as "answers".
Article on the Pending oil peak with some discussion of sociological effects.
The Social Contract Press A conservative group view of the issue.