Great ideas! I will try not to duplicate...
Buy bulk for things you will actually use up.
Make your own when possible--I can get 4 cups of dried mung beans to sprout about 4 gallons of sprouts for $3. One tiny container of sprouts costs about $3. Make my own pancake mixes, dressings, hot cocoa mix, chai, etc.
Avoid plastic and paper products, especially disposable dishes. I "invest" in reusable containers like Wifezilla has mentioned. That way my kids don't go through about 8 plastic baggies per day for lunch
Pack lunches. My kids get the basics--leftover soup in a thermos, sandwiches with applesauce and carrots, etc. Not much fancy stuff. No Go-gurts, chips or other expensive foods.
Grow your own food! We save so much money doing this, it would be hard to calculate. Our freezer had about 50 quarts of sweet corn, 25 quarts of applesauce, 15 gallons of berries (or more), jam, Swiss chard quiche mixes (6), chickens (about 25) and so much more. You can save crazy amounts of $ growing and processing your own food.
Buy generic.
Try to stick to the necessities. Great ideas on planning menus! I will really have to try that. Like Wifezilla, though, one of my joys in life is making whatever sounds great that very day.
Similar to above, try to avoid soda, chips, candy, premade meals, ice cream and other "junky" foods that are very expensive and not necessary. Chocolate, however, IS necessary! I'm not saying don't have treats--just that having these things as treats rather than an everyday item can save a lot of $.
Just what I can think of off the top of my head...