Wow, lot's of hostility to my comment, and a few good points too.
Boats - I stand corrected, boats have some modest emissions controls. We could definitely stand to see something stronger though:
Planes - Yes, I understand that the U.S. is large, but we can start with modern trains that connect smaller distances, like Milwaukee to Chicago, L.A. to Vegas, etc. Trains are more efficient than planes, and can actually travel very fast. I'm also speculating that trains suffer from fewer delays, have quicker security checkpoints, and require less maintenance.
Coal power plants: There is no such thing as clean coal plant. Look at the destruction caused just to GET the coal, let alone burn it. It's dangerous for the workers and disastrous for our environment. Search for images before and after mining, it's unsettling.
Lawn Mowers - Operating a mower for an hour is the pollution equivalent of driving a car 200 miles. Consider how many lawns are in the U.S. alone. That is not insignificant: http://www.epa.gov/oaqps001/community/details/yardequip_addl_info.html.
Excessive Water Consumption - Too many people underestimate the value of clean, fresh water. It takes energy and costly equipment to clean and deliver fresh water to your home. Water is also a limited resource. If/when our rapidly draining aquifers run dry, the consequences will be disastrous to our food supply and economy. We can do some simple things to reduce our usage, without much effort. Front load washing machines save ~20 gallons per use. Low flow toilets can save ~2 gallons per flush. I have no regrets switching to either, and I have a lower water bill. http://environment.nationalgeographic.com/environment/freshwater/water-conservation-tips/