My contribution to Blog Action Day (http://blogactionday.org/) is my renouncement of diet sodas in favor of plain old water. Not bottled water ... tap water. Considering the number of diet sodas I used to drink (5-6 per day), the plastic saved alone should ensure my place in Environment Heaven.
OK, OK, I didn't originally do this to save the environment. But since I was doing it anyway, I thought I might as well take credit for being environmentally correct, too!