Thermos bottles were designed to keep hot beverages from cooling down so workers could have a hot cup of coffee all day long. Their insulating properties make thermos bottles ideal to cook foods that take a long time to prepare such as oats, dried beans, and whole grain cereals. Simply bring your ingredients to a boil and pour everything into the thermos and give it time to cook.
Of course you can use a slow cooker to do the same thing, but the advantage of thermos bottle cookery is that it is portable and doesn't require electricity. This makes it to use when camping or just to prepare steel-cut oats before you leave for your commute and having a hot breakfast when you arrive at work.
The source link below has many additional resources for thermos cookery such as recipes and nutritional information.