A few links:

http://www.getrichslowly.org/blog/2009/03/25/how-to-save-100-or-more-at-the-grocery-store-this-month/
http://www.getrichslowly.org/blog/2008/06/30/saving-at-the-supermarket-15-great-grocery-shopping-tips/
http://www.getrichslowly.org/blog/2007/07/24/save-on-groceries-with-strike-point-shopping/
http://www.getrichslowly.org/blog/2008/03/12/the-lazy-mans-guide-to-groceries-on-a-budget/
http://curbly.com/DIY-Maven/posts/2289-Top-2-Ways-to-Save-Money-at-the-Grocery-Store#jump

One thing I always do is check the price per unit of something (so for example, cents per pound, or cents per fluid ounce, and so forth) rather than just going by whatever is cheapest or trying to visually figure out which one of multiple brands is the best value.

This may be common sense and everyone does it already, I dunno? I just know some people who look only at the price of things and grab the lowest price item, even if that item's price per pound is well above other items (and therefore, they're actually paying MORE).

For me, at least, that saves a bunch over the long run.

There's also other more obvious things like, don't go shopping when you're really hungry, as you'll likely buy more than you typically would (although don't go when you're stuffed either, as you'll end up not buying enough... works both ways). Also, try to go on a weekday afternoon if possible, to avoid crowds which leads to slowdowns and more "impulse buys."

Grocery stores are full of psychological traps to get you to buy more. The slow music, the crowded isles (they leave those pallets of food in the middle of aisles on purpose... to slow you down), necessity items like milk and eggs at the back of the store, candy and cereal in the same aisle, etc. It's really a behavioral experiment masterpiece, knowing their tricks sometimes helps you avoid falling for them.

Everyone's ideas are good.

A tip: use a grocery list and do NOT go grocery shopping when you are hungry!

Buy whatever you can in bulk! It's often significantly cheaper. And if you can buy some jars to put the things in, your kitchen and cupboards will look much nicer than if you only had things in packaging. Ikea has cheap containers, but you can also find Mason jars around town.

Write out a meal plan and then do a list from it. Go to the shops once per week and only buy what is on the list. And be very clear about what you need, rather than want. If you have kids, try not to take them with you to the store, so much of the marketing UF refers to is directed at the kids.
Same with household items - list what you need and only buy the things on the list.

Maybe its obvious, or at least old fashioned, but coupons can save a lot of money. I buy the Sunday paper almost every week. As long as you stick to things you normally buy anyway and if you can combine them with sales at the store that's even better.

Buy in bulk and freeze-- meat, veggies and fruit can all be frozen and thawed for later use, and most of it will last for months when frozen.

Buy in bulk rather than prepackaged (they sell everything from granola and nuts to beans, pasta and flour in bulk, and it's usually cheaper that way.

Hit up farmers markets, or at least buy in season produce, which is usually cheaper than grapes or peaches shipped from half way across the world (plus better for the environment).

As others have mentioned, buy whole, unprocessed foods, if it's been processed, it's probably more expensive (and has less nutritional value).

This may be obvious, but buy off brand or store brand items instead of name brand, since most products are fairly similar anyway.

Shop at discount food stores like Grocery Outlet, some stuff is funky, but you can usually find great deals on things like tea, crackers, juice and other stuff that doesn't go bad too quickly.

Check out new recipes that involve hearty foods like beans, lentils or garbanzos that provide a lot of sustenance for a low cost (much less than meat, for example). A giant pot of soup with one of these as the base can usually be made for a few dollars and last several days depending on the size of your household. Also, soups freeze well!

Learn to preserve food (freeze, dry, can). Tis the season for lots of fresh local fruits and veggies which when canned will last you throughout the year. You can learn for free from the Master Food Preservers (http://www.preservefood.com/masterfoodpreserver.shtml) and all you have to do in return is teach someone else.

If this is a long term goal, think about starting a garden, or if you don't have space, getting a plot at a community garden in your area. This requires some investment in time, but is well worth it in savings. Plus you also save on gas and it can be a fun activity for the whole family.

If you're really struggling, check out a food bank in your area, or projects that do gleaning, especially during the summer. Many such projects will allow you to volunteer your time but keep a portion of what you harvest for your own use if you are low income.

Good luck!

generally you trade time for a cheaper bill. Some people's time is more valuable than the savings, I guess. But if not:

Utilize Grocery outlet / costco / TopFoods rather than WholeFoodsInc or other spendy supermarkets (Safeway)- UNLESS you are eating organic only, in which case you'll have to hunt around and find the best deal (Madison Market wins some of the time, WF wins other times)

Buy nonperishable items in bulk when on sale and store them.

Buy fresh produce at the farmer's market

Check price per unit or price per pound (like on nuts, cheese, etc) and make sure the 'sale' item is really a good deal.

Don't buy "prepared" meals. Pre-spiced beef, pasta roni, lean cuisines, any of these are bad values.

Make your own bread - it's not very hard, and it will always beat the fawking 4 or 5 bucks a loaf QFC charges.

Walk to the store, preferrably not the one closest to you. You are less likely to buy things you don't need if you have to lug them home.

Last resort: eat less. ;)

I buy all my food online, like safeway.com or amazonfresh. That way I completely avoid spontaneous shopping and get exactly what I need.

I agree. Check out the weekly savings flyers from all the stores and only buy on sale what you would normally buy. I should have been hip to this long ago, but wasn't. I used to buy whatever I could afford whenever I wanted it, and my food bill was hundreds more than it needed to be because of it. But beware! Not everything in a circular is really a sale price. If, for instance, chicken breasts are advertised for $2.99/lb., that's no big deal. If they're 99-cents/lb., stock up!

In other words, there'll be good weekly buys, but you'll still have to examine circulars carefully for gimmicks. I hate it that grocery shopping has become this boring game, but my wallet says to me, "Thank you!"

And let's face it: Some stores are like highway robbery unless you are very price conscience. They love it when you "run in" for milk, bread, and eggs and wind up spending 50 or 60 dollars on impulse.

One thing you may not be aware of is that some stores that have a lot of bulk bins have stuff in there you might not think of, like dried pasta and breakfast cereal. And always at a very large savings. It's not just spices 'n' rices like it is at some stores.

One thing I've found just recently is bulk dried refried beans. Reconstituted they are not 100% as good as canned refried beans, but they're close enough, and you can always make the quantity you want -- when I'm making lunch for myself a whole can is way too much, and there are few things less appetizing than a half-can of leftover refried beans in the back of the fridge. Making them from scratch is awesome but not practical for everyday.

#1 rule, though, is never buy anything that comes in a box or has more than three or four ingredients. Prepared food is rarely a good deal. Frozen is OK -- properly prepared, frozen vegetables have more nutrients than fresh in many cases (because "fresh" is rarely very fresh, and soft, stale veggies have lost much of their food value) and taste just as good -- AND they don't rot away in your fridge bin when you forget that you bought all that kale that you're going to throw away now. Reducing the amount of food you buy is part of the solution; reducing the amount you throw away is another.