Many people are concerned with Energy Depletion, usually calling it Peak Oil, although all fossil fuels are involved.  There are quite a few sites to follow. 

For the geologist's slant, I prefer The Oil Drum.

For a wrapup of relevant headlines, Energy Bulletin is invaluable.

Last September, I attended Congressman Roscoe G. Bartlett's
Maryland 6^th District 2005Energy Conference
Peak Oil " Facts, Implications and Challenges:
Dr. Kenneth Deffeyes: Hubbert's Peak Inescapable Facts
Matthew Simmons: Today's Realities
Richard Heinberg: Impacts and Challenges
Sustainability "What Must We Do To Achieve A Soft Landing?"
Donald Wulfinghoff: The Key "Energy Efficiency"
John Spears: What Does Sustainability Look Like?
John Howe: Understanding the Challenge "Critical Priorities"