You asked for it, and now you're gonna get it... I don't think any of these ideas are revolutionary, and I'm sure many of you have already implemented some of them or all of them. They have helped me, though I often forget about them and have to go back from time to time as a refresher.
1. Set a weekly amount and stick to it. Figure out what you can really afford to spend that'll still feed your family, and don't deviate from it more than $5. If you think you have more food in your cart than that amount, stop, think, and put something back. Avoid the urge to spend more than your amount one week, thinking you'll spend less the next. It usually doesn't happen that way, at least to me it doesn't. Cut yourself some slack if you're feeding a lot of extra people or hosting a party, but for normal weekly meals, even with one company meal in there, try to stick tight to your set limit.
2. Buy generic, and don't buy many convenience foods. There aren't many brands that I buy. Most things in my grocery cart are going to be the generic brand. I admit that there are some things I can taste a difference in. I buy Kraft mac n' cheese for our Sunday night supper, (since that's one convenience food that's ridiculously cheap), but I won't buy the store brand because I've tried it, and it's awful. But most items are cheaper in the store brand, and most are just as good as the name brand. I don't buy name brand diapers, and they're just as good as Pampers, though they don't smell as good. =) When I say don't buy convenience food, I mean don't buy prepackaged meals or mixes very often. If you're going to eat out if you don't have one in the freezer, then buy them, but if you can make your own freezer convenience food instead, that'll save you money.
3. Don't let anything in your fridge go to waste that you can use for another meal. For instance, when I buy a loaf of bread lately, I immediately freeze it. That way we won't waste it if we don't use it right away. The same goes for leftover hot dog/hamburger buns. I freeze them, and then we can have hamburgers for dinner one night later on. The same goes for tortillas. They freeze well. Shredded cheese freezes well, too. I buy shredded mozzarella in big bags and freeze it in 2 c. servings for pizza.
If I make something, and it makes enough for another meal, I freeze the leftovers, and I put them in the meal rotation for a couple weeks down the road. That way they don't go bad. Some people send leftovers to their spouse for lunch. If you can avoid doing this, I'd advise it, unless you plan to serve yourself lunch for dinner one night later on. David and I eat sandwiches, a piece of fruit, carrots (cut in sticks and put in water in the fridge), and some cheese crackers or pretzels every day for lunch, or crackers and peanut butter or cheese, etc. This is the cheapest thing you can do for lunches.
Oh, yeah, don't just freeze odds and ends of things and forget they're in there. Go into your freezer and look around before you make your meal plan for the week. Use what you have, whether it's there or in your pantry.
4. Embrace Mexican food. Why, you may ask? Because our Latin friends to the south have perfected the art of stretching meat and using beans. Mexican food is cheap. You can stretch it by adding rice and beans. Tonight we're having black bean and cheese enchiladas for dinner. Dirt cheap. I have frozen beef and bean enchilada filling by the truckload. 'Nuf said.
5. Eat less meat, and buy some of it in bulk. I'm not too proud to buy my meat at Super Walmart, and if I freeze it as soon as I get it home, I think it's just fine. I buy gigantic packages of lean hamburger and split them into 1/2 lb. bags for freezing. I do the same with stew meat. I use less meat in my recipes, and I waste less by doing this. If we want to have hamburgers, I can thaw one 1/2 pound package, and that'll make 2 hamburgers for two people. If I thawed a pound, some would go to waste. We also don't have a wide variety of meats because kinds other than stew meat, hamburger, and chicken are more expensive. I try to plan a large meat purchase into my budget so that I don't have to go over that week.
6. Buy frozen vegetables instead of fresh. Frozen vegetables have all the nutrients of fresh, but they don't go bad as quickly, and they're cheaper. Canned tomatoes have the nutrients of fresh, sometimes even more, and they're cheap and healthy.
7. Love some soup this winter. I have several soup recipes I love. As long as you don't make them with potatoes, you can freeze them for later. I freeze my soup in one bowl portions so we have choices. David and I don't even have to have the same soup for dinner if we don't want to! Soup is cheap, healthy, and easy!
8. Eat less cereal. Cereal prices are rising all the time. It's really quite expensive when you think about what goes into it. David likes to eat two bowls of cereal for breakfast. We're working on breaking this habit, and him eating one small bowl of cereal and some toast with jelly. For the first couple of years of our marriage, David ate toast for breakfast exclusively. No cereal in our house.
9. Oh yeah, plan your menu for the week before you go shopping. If you go more than once, you're more likely to pick up "extra" items you don't need. I write out my menu for the week on Monday mornings. I try to put several freezer meals and at least one vegetarian meal on there. I also plan for one meal I wouldn't mind serving to company, so we can be hospitable in a pinch. We have something cheap and trashy on Sunday nights like mac n' cheese with cut up hot dog in it. =) I look at the menu and try to make sure I'm not buying more than one kind of meat in a week. That'll blow my budget right there. Spacing things out is important so you don't get discouraged and give up.
So there ya have it, my tips for saving money on groceries. I'm sure there are plenty of others out there that I haven't thought of, and there are plenty that I'm not willing to do just yet, like using powdered milk instead of real milk. Blech. Try http://www.hillbillyhousewife.com/ for more ideas. She goes places that many women have not boldly gone before her. She's got some great stuff, though.