I concur with the person who suggested Baked Beans. Bean and Cheese sandwiches are awesome (and I guess you could use the tins of beans with little sausages in, if you like that sort of thing).
Tuna melt sandwiches are good. Bread, bit of salsa (or failing that, ketchup) spread on one slice of bread, half a tin of tuna, and bit of cheese. Delish.
Also, my personal favourite is Fish Finger Toasties. Grill about 3 or 4 fish fingers. Butter the outsides of your bread, and spread tartare sauce on the insides. Add the fish fingers, and cook for about 3 minutes.
If you're interested enough to spend some money, there's always Toastie Heaven!