General Electric Co. (NYSE: GE) and Wal-Mart Stores, Inc. (NYSE: WMT) are two well-known companies at the forefront of "being green." In GE's case, the company manufactures a wide range of eco-friendly products, from wind turbines to light bulbs that use less wattage per bulb. And Wal-Mart is trying to make its stores, trucking fleet and even retail products green-friendly while helping its customers do the same.

GE CEO Jeff Immelt said recently that he "works for investors." This was in response to questions about the U.S. government being increasingly involved in regulating greenhouse gases produced by corporate America. Said Immelt, "Look, I've never voted for a Democrat!" At the same time, GE takes government subsidies for making its eco-friendly wind turbine products, a fact brought out by a question Immelt took at the first-ever ECO:nomics conference in Santa Barbara, California.

Green energy and eco-friendliness were some top themes on consumer and business minds in 2007, and this will most likely continue into 2008 and in the coming years as well. Given the huge increase in fuel prices in the last 36 months, it's no wonder that investors have pushed up the shares of these companies.

Alternative and green energies will, in my opinion, be an investment area that should demand attention this year if you are ready to expose your portfolio to what is not a trend at all, but what is becoming the future. There's a reason why General Motors Corp. (NYSE: GM) and Toyota Motor Co. (NYSE: TM), for example, continue making statements about vehicles that run on anything but gasoline.

Although 2007 saw great returns with renewable energy stocks, 2008 holds the same promise. Looking for areas in which to research and invest? Start by focusing in on companies within the WilderHill clean energy index (which contains 48 renewable energy stocks). The index was up 58% in 2007 after single-digit gains in 2005 and 2006. While solar power stocks already saw a huge increase in 2007 (some with 100% returns), that arena may take more careful scrutiny for 2008 if you're looking for market-leading stock performance. At the same time, wind energy stocks are poised for larger returns in 2008 in the game to lead market returns for all renewable energy stock categories.

Toyota Motor (NYSE: TM) beat up on General Motors (NYSE: GM) in 2007, and the company wants 2008 to be the year in which it officially becomes the world's largest automaker by sales volume. To kick off the new year, company CEO Katsuaki Watanabe recently released Toyota's resolutions and initiatives for 2008.

Watanabe highlighted the plight of global warming to start his message off. Surprised? Don't be -- he then indicated Toyota would be involved with three areas of sustainability in 2008: research and development, manufacturing, and social contribution. Watanabe's concentration on the eco-friendliness of the auto industry to begin his 2008 initiatives hinted at where the company was going with its hybrid automobile focus. Sure enough, Watanabe said that Toyota wanted to have a hybrid model in all consumer vehicle model lines in Japan as soon as possible.

But then, Watanabe dropped quite a large hint that Toyota was becoming heavily involved in the manufacturing and design of batteries and alternative energy research. This makes sense, as current hybrid models need to increase in the cost/benefit arena if consumers are ever going to be swayed to purchase them en masse. Watanabe also mentioned Toyota's involvement in "sustainable mobility" as it applies to infrastructure and energy.

In essence, Watanabe's entire message for 2008 centered on alternative vehicle propulsion and energy generation more than anything said about the competition. Will Toyota become the biggest "green" company on the planet through its efforts? When it comes to one of the larger contributors to greenhouse gases -- automobiles -- it surely could. Will its efforts pay off with more sales in its global markets? Shareholders hope so.