Well now there is a website designed to help. http://www.toptenusa.org/
I found out that my recent dishwasher and laptop purchases were both in the top ten.
From their website -
TopTen USA is a nonprofit organization that identifies and publicizes the most energy-efficient products on the market. We make it easy for consumers to find the most energy- and money-saving models, which in turn encourages manufacturing innovations that will make products in the United States even more energy-efficient.
Modeled after organizations located in 16 different European countries, TopTen USA intends to transform the American market from the one of excessive energy use to one that actively sustains products with the highest practical energy-efficiency.