Peak Oil 

Life After the Oil Crash - Hosted by Matt Savinar, JD.  This is a well researched site with many links to the sources that are used.  He tends towards pessimism, but if things shake down like he suggests, then future prospects are not exactly rosy.

Peak Oil Debunked - Don't be confused by the name.  It does support the theory that Peak Oil is an inevitability, but questions the assertions of those he calls the "doom and gloomers".  It is a good read that is both well researched and well thought out.  A must read for folks new to the topic to get additional points of view.

The Oil Drum - Run by academics and scientists well read in the area.  Attractive and easy to navigate with a plethora of links. 

The Hubbert Peak Theory - via Wikipedia, addresses the history of the Theory and its application to US and world oil fields.  It also examines the economic factor driving Peak Oil and the Theory's application to other models.

PeakOil.com - A solid website rife with info, links, and what seem like a fairly balanced approach to the issues.

The Energy Bulletin - Thorough and simple, this site offers a good Peak Oil primer, and covers the topic of alternative energy sources quite well.

Energy Resources

Fox News Energy Page