First off, you guys are overestimating the power that the president has. The president cannot pass a law. The president can sign bills into law. That's about it. He can propose laws to Congress, but he cannot singlehandedly pass them into law.
That said, I would decrease the amount of government red tape ski areas and other businesses running on National Forest land would have to go through to expand their operations.
I would also work to end the US's addiction to foreign oil by creating incentives for electric cars (i.e. Chevy Volt) and other zero-emissions vehicles (ZEVs). The goal would be to make every new car produced, built and sold in the United States a ZEV by 2060. As part of this, I'd also work to usher out coal, oil and other heavily emitting power plants by the same year (2060) in favor of nuclear, geothermal, hydroelectric and wind power. Finally, I'd create incentives for private companies to develop other renewable energy solutions (i.e. solar panels on the moon w/ microwave back to Earth). That way, the government is only establishing the framework for change while allowing free enterprisers to cash in on a potentially lucrative business.