I have not been as good about this as I used to be in the past. And a few times I've thrown things in the freezer in a hurry without labeling thinking I'll remember - yeah, fat chance. How I ended up with liver defrosted when I thought I was pulling out veal. I don't really make and freeze casseroles or complete meals. I will freeze left over stew (sans potatoes) and chili. Soups we pretty much always eat up.
I do always have frozen meatballs - a lifesaver for spaghetti dinners, sandwiches, or hearty but quick soups. I buy pork and rib-eye sliced for bulgogi, divide it into smaller packages, so can make stir-fries and other things that call for thinly sliced meat very quickly - as well as bulgogi.
I also always have frozen hamburger patties in the freezer. I will fry from frozen for a quick hamburger or cover with a mushroom gravy for a patty dinner or thaw two patties to make
30-Minute Chili or a soup. They thaw quickly in the micro if I did not think to take out earlier.
I also freeze two link portions of sausage - Italian, bratwurst, greek - sometimes fail to label them, but that's the breaks - and those are good for pasta or soups.
Frozen dumplings - Asian, Lithuanian, Polish - are good for a quick meal. Also frozen scallops are good - they thaw quickly and just a few make a nice serving.
In the past I used to do more, but these seem to be the most useful things for me to be doing.