I also really dislike wasting ingredients and groceries. It pains me to find slimy cilantro in the refrigerator drawer. (My remedy for this, is to SHARE the bunch of cilantro with a friend or neighbor after taking what I predict my recipes for the week will require.)
And the freezer is a great remedy for extending the life of foods.

Bananas: If you have bananas that are really getting ripe (and you don’t have enough to make banana bread or time to make it), you can peel them, put them in a Ziploc bag, and stick them in the freezer. They can be thawed for banana bread making and are perfect for smoothie making - adding a thick, frozen creaminess.
Bread: I keep most of our bread in the freezer, so that it has a life beyond a few days. This is true for sandwich bread, when we are in a season of sporadic sandwich eating as well as artisan (crusty) bread, which doesn’t contain preservatives. I just leave half in a bag on the counter and the other ½ zipped away in the freezer. Then when we are ready for the “new fresh installment”, I just set it on the counter and in a few hours it is like day 1 bread…all over again.
Onions: When I am using part of an onion, I oftentimes go ahead and chop the entire onion, bag it, label it and freeze it. It can be thrown into the saute or soup straight from the freezer next time you need ½ a cup of chopped onion. It is so handy and prevents dying onion from stinking up your refrigerator.
And you can freeze cheese.
And don’t forget leftover pancakes.
And it goes on and on and on…
Now I must warn you: freezer storing candy bars does not necessarily extend their life as I seem to like them EVEN MORE when they come right out of the freezer!
(stay tuned for Post #3 about Muffin Making)