This is how I manage my pantry, grocery shopping, and coupons...
I have a word document for each month of the year. Each document has a calendar on the first page and a pantry, freezer, fridge inventory list on the second page. It took some time, but typing up the inventory of the pantry, fridge, and freezer was well worth it. I cut/paste the inventory list when we finish a month and move onto the next...
So for a given month, I start filling in meals (mostly dinners, as our breakfasts and lunches are the same). At the end of each day (or beginning), I update the inventory list with what was eaten or used up that day. Stuff that needs to be used up soon, I change the font color to red! So when I make my shopping list for the week, I look at both the menu plan for the week and the inventory list. The menu is constantly tweaked based on what needs to be used up. Also, I pull out any coupons that are going to expire before my next shopping trip or for things I need to buy and paper clip them to my shopping list so I know to use them. I keep all my coupons in an envelope in order of the store layout. That way as I'm going up and down the aisles, if I see a sale for an item that I have a coupon for, I'll know to buy it.
Since I started this method, I almost never throw anything out and we save a ton of money by not eating out so often. Oh, I also have a pasta meal that we always have the ingredients for. That way if I miscalculate how much food gets eaten/used up I have an extra meal to fall back on. Less trips to the store means less money spent!