Food items most used:

Tortilla shells - hey, when that bread gets crushed or starts growing mold, those trusty tortilla shells are a great replacement.  They store unopened without refrigeration, and when opened, take very little room because they are so flat.  Use the shells for quesadillas, burritos, fry them for tortilla chips, or just make your sandwiches, "roll - ups".

Boullion Paste - Found this boullion paste in a jar.  One teaspoon is equivalent to one bullion cube.  You can use it to make soups, sauces, spice up a bland can - of - something, or even a dip when you have yogurt or sour cream.

Canned soups - Nothing tastes better after a full day in the cold wind that a quick bowl of mushroom soup or clam chowder.  The down side is the bulkiness of the can in your trash area, but stock up on some of these for a quick meal. 

Dehydrated mushrooms -  I bought some dried whole shitake mushrooms at Costco, and after soaking in water 6 mushrooms is more than enough to liven up a side dish, cook with pasta, bulk up a cream of mushroom soup, or serve grilled with another veggie.  They store well (come in a large plastic screw top jar) and are virtually indestructible.

Nuts - Cocktail hour, mid - sail snacks are really easy with a nice assortment of nuts.  They provide good protein, are easy to store, and again, virtually indestructible.