You've already gotten a lot of really great suggestions.
One thing you can do to really significantly reduce your environmental impact is to reduce the amount of meat you eat, especially from "ruminants" like cows. They require a lot of land to feed, and their waste releases methane (a greenhouse gas) into the environment.
Join a CSA (community supported agriculture) group. They offer locally grown organic produce on a weekly or bi-weekly basis.
Avoid dryer sheets altogether if you can. If static is a problem, vinegar is supposed to work as a fabric softener (I've never tried it, though).
Make your own laundry detergent. There are lots of easy recipes on line: http://www.thefrugalshopper.com/articles/detergent.shtml It's much cheaper than buying detergent at the store, and it saves on packaging.
Wash your clothes in cold water.
Use cloth napkins instead of paper towels and napkins in your home.
Bring your own silverware with you instead of using plastic cutlery when you go out to eat.
Go to catalogchoice.org and get yourself removed from the lists of companies who send you unsolicited catalogs.
I have a friend who has all her major electronics plugged into a few power strips. Every night she unplugs them all. Even when appliances aren't being used, they hold some of their charge. (Same with those cords with the power cubes on them.) She says that turning off these appliances every night has saved her a lot of money, and obviously it is more energy efficient.
Buy less stuff altogether. Make do with less. Every time you buy something, you generate waste that comes with the production, packaging, and transporting of the new item, not to mention the disposal of the item you are replacing.