It's tough to beat the kind of year Exxon Mobil had in 2011. Shares rose by 20% and profits surged by 35% to $41.1 billion. Revenues jumped 28% to $452.9 billion, helping Exxon reclaim the top spot in the Fortune 500.

Exxon has certainly benefited from rising oil prices, particularly during the last quarter of 2011. But the company has also positioned itself well to capitalize on the latest controversial trend in domestic energy production: Fracking. Exxon now produces just about as much gas as it does oil, thanks to its $35 billion purchase of XTO Energy in 2010. As CEO Rex Tillerson told Fortune recently, with world demand for energy expected to rise considerably during the coming decades, the shale gas party has just begun.