One essential element of being frugal is that you use what you have, the best that you can. Other people have said this over and over too--Amy Dacyczyn said that she didn't want to print her recipe for pumpkin-blueberry muffins because those things were cheap/free for her but not necessarily for other people. (And yet people are still after her to write a cookbook.)
And that's one reason it's difficult for me to plan menus ahead of time, because the leftovers from pre-planned dinners have to get accounted for too. Coffeemamma just posted a very sensible week's plan and notes that it's based on what's available to her this time of year. We are in that same kind of waiting-for-the-fresh-stuff place right now.
I find the type of groceries we have really varies, depending on where we've been shopping. Last weekend the weather was bad, Mr. Fixit wasn't feeling well, so we were limited to a Giant Tiger trip plus a stop at Bulk Barn. I wasn't about to pay $2.89 for celery at Giant Tiger (although I've noticed that it's expensive at other stores right now too), and for the rest of our vegetables I had to settle for frozen peas, a can of mushrooms, and a head of iceberg lettuce. (I already had carrots and onions.) I knew we'd stock up better later on, but that was what we had to work with for at least a couple of days. Anyway, all that is to say that we had a few a-la-can dinners this week, which isn't necessarily a problem--it's just that sometimes what you have is fresh, sometimes it's frozen, sometimes it's packages, and you have to plan your meals on your feet, so to speak. (Remember my food-box menu plan? In a similar vein, I like what the new Hillbilly Housewife is doing with the Angel Food Menus, based on what's being distributed through another food box plan.) One night we had Giant Tiger's frozen cabbage rolls, plus a package of wieners that I put, frozen, into the oven with a bit of barbecue sauce over top; later I added a can of baked beans. Last night we had chicken spaghetti, with a salad made out of the iceberg lettuce, grated carrot, and sunflower seeds.
And sometimes you just do what makes sense. I've had a bunch of things to do today plus I have a meeting tonight and I don't want to leave a lot of pots and pans. (The Treehouse doesn't have a dishwasher.) We have ground turkey and I was going to make turkey loaf and maybe have mashed potatoes and vegetables with it...then I thought of the loaf of bread that just came out of the breadmaker, and the homemade cream-soup-mix in the cupboard, and the bag of frozen Japanese-style vegetables we bought last night (we did go on another grocery trip--worth a post in itself), and I thought--Hot Turkey-Vegetable Sandwiches. Or Turkey a la King on fresh bread, or whatever you want to call it. It's not a meal I'd make all the time, it's just what works today. (I also had a gi-nor-mous sweet potato from last night's trip, and I cut that up (so it wouldn't take forever to bake) and put it in a pan in the toaster oven.
That's not exactly a leftover story, but leftover-using-up works the same way. Last night's dessert was a what-do-we-have story: plain yogurt (frozen in cubes but mostly thawed by dessert time), one small blueberry yogurt cup, some frozen blueberries and mixed berries (leftovers of each), and graham crackers. Recipe: break up the graham crackers and layer them in a glass bowl with the yogurt and fruit. Let sit until defrosted but not entirely mushy. Call it trifle.
I could have skipped dessert for tonight, but I had some crushed pineapple getting forgotten in the fridge, and part of an orange that nobody finished at lunch. I cut up two bananas, spread the fruit all out in a small pan, and stuck it in the freezer. At dessert time we'll run it through the food processor--instant sherbet.
(Well, I guess that does leave a few dishes. But you get the point.)