Loss leaders are items that stores offer at a loss in the hopes that the low price will get you into the store and while you're there you'll buy the rest of your groceries at regular prices. Some examples of loss leaders we've seen recently are chickens for 29 cents a pound, center cut pork chops for 99 cents a pound and 3 liter cans of olive oil for $6.99 (regular prices for these items in our area are 99 for chicken, 2.99 for pork and $18-$20 for olive oil). When your store offers loss leaders buy as many as possible and stock up. If they offer tomato sauce at 10/$1.00, buy them even if you don't plan to make spaghetti right away. They'll keep and you'll be glad you have them when you see the price go back up to 25 or 35 cents a can.
If you have more than one large store in your area they will usually offer different loss leaders so by going to a couple of different stores you can do really well!