For me, when I making a casserole, its almost as easy to make two as it is one. I double the recipe and pop one in the freezer. I label it with the name, date and cooking directions. When I know I'm going to have a busy day, I pull it out of the fridge the night before so dinner is ready to go. Another bonus, if a friend is in need of a meal, I already have something ready to go!
There are a ton of great cookbooks on batch cooking and freezer meals. On of my favorites is Fix Freeze Take and Bake.