Twice baked potatoes. Bake potatoes (I use the microwave) cut them in half, scoop out the inside. Add whatever you want, sour cream, butter, milk, cheese, cream cheese, scallions, bacon, broccoli, etc. Mash them up, put the filling back into the potatoes and throw them into the oven to heat through.
I also like to thinly slice them and grill them on tin foil with butter or oil, salt, pepper and garlic powder. Really you can use any kind of spices on them, paprika, rosemary, etc..
Fried potatoes (or home fries) are always good too.
I also like to grate a whole, peeled potatoe, wrap the grated potato in a clean dish towel, squeeze out the water and fry it like hash browns.