Quick Idea: Sometime a simple change is also a big change.
Check out Danni Brancaccio’s blog about her quest to go all summer on one tank of gas, simply by changing her habits.  Granted, she sometimes borrows her mom’s car (per CNN).
Resources
Simple Human 101 ways to use less gas
Freakonomics on The New York Times Hurray For [...]

Quick Idea: Most Wine Should Be Sold in Boxes from Daring Fireball.
“Switching to wine in a box for the 97 percent of wines that are made to be consumed within a year would reduce greenhouse gas emissions by about two million tons, or the equivalent of retiring 400,000 cars.”
Even though it’s simpler and helps the [...]