I'm not sure how much we actually spend a week on groceries. It depends on what your definition of "groceries" is. Food only? $50 a week, easy. Anything you get at the grocery store? Well.......
I go shopping at the first of each month (right after payday). I go to the grocery store and spend $250-320 (depending on how much meat I have to buy), then I go to WalMart and/or Orscheln and spend another $50-100 (total). So it's probably more like $100 each week if you divide it out, but this includes everything - food, diapers, personal care, household (kitchen utensils/gadgets, storage, etc.), cleaning supplies, pet food, garden supplies.... Then I pay all our bills also at the first of the month, so everything is paid up, and all we have to worry about is gas for Paul to get to work. (I have only been using 1 tank or less of gas each month.)
I usually make one more trip to the store, for milk, or for a special meal (either having company, going to someone's house/church dinner, or Paul requests something I don't have all the ingredients for). So I spend a little more one or two other times each month, although the boys' milk consumption took a nose dive with the hot weather, so that has helped.
So I don't know how that compares to the average household, but that's our life.
Things we eat a lot of, that I know helps the ol' budget:
Hot dogs. The boys eat these for lunch more often than I'd like to admit. (I stock up when they are $1 or less/package.)
Rice. I add 2 cups (uncooked, so 4 cups cooked) instant brown rice to lots of our meals. Tacos are 1 lb. meat, 4 cups rice, and 1 can beans. Stir fry also gets 4 cups of rice. Salisbury steaks. Chinese hash. Tater tot casserole. As long as you add extra seasoning so the rice doesn't dilute the flavor, rice makes meals go SO much further.
Beans. As mentioned above, I put beans in tacos. We also have meatless tacos where we use beans. (Recipe here.) The off-brand beans are only 50c a can.
White pasta. I have 5 jars on my counter, each for a different type of pasta (rotini, penne, fettucini, spaghetti, and rainbow bow tie). We eat lots of it. I know "carbs are bad" but carbs are also cheap. Some noodles, a bit of butter, and some Mrs. Dash (or other herbs and parmesan), and you've got a super-simple, super-cheap side dish. Add some pepperoni or smoked sausage, and you've got a main dish. (Paul and the boys are the real fans of butter noodles. I'm more into noodles drowned in sauce.)
Leftovers. Very rarely do I throw away food. If we're having trouble cleaning something out of the fridge, I simply don't cook until it's all gone. Paul takes leftovers in his lunch to work, and the boys are really good at eating them, too.
I guess simple (lazy) is my deal. I don't get excited to make gourmet meals or try new things. If it's stuff I already have in the house, I'll try it, but if I have to go buy fancy ingredients, I usually don't bother.