We didn't do anything in particular yesterday but we always:
Buy organic and/or local produce, when possible
Avoid any and all prepared food products, when possible
Avoid items with fake fragrances, such as colognes/perfumes, air fresheners, deodorants etc
Avoid harsh cleaning agents such as bleach, normal soaps/detergents, oven cleaners, fluoridated toothpaste
Plant some veggies on our balcony, no chemical fertilizers or pesticides (I can see why pesticides are popular though...after the great Earwig balcony invasion of 2008)
Use biodegradable stuff when possible, dog poo bags, cat litter etc
Reuse bags
Walk (although...we don't have a car, so this doesn't really count since it is either walk or take the bus, and the bus runs regardless...)
recycle
Stuff we should do: turn off computers, take shorter showers....can't think of anything else atm