A hot water faucet on the outside of the house to wash coolers and large items that are too hard to do inside.
A mud room.
Power outlets under the eaves of the house if you like to put up Christmas lights
A 240 Volt outlet in case you need to plug in an RV
If you live in a place that could lose power due to a hurricane or snow storm, a plug in on your breaker panel that allows you to plug in a generator to run the essentials until they can get power restored.
If you have an open concept living room/den, plug-ins on the floor so you can have power in the middle of the room if needed.
Double doors leading to the backyard in case you have big items you need to get in the house like couches or gun safes that don't fit easily through regular doors.
If you live in a area prone to tornados, a safe room like a closet with reinforced concrete or center block walls. Also works well to put a safe in to store valuables like guns, jewelry etc.
If you live in an area where the ground doesn't cause issues like flooding or shifting, basements are awesome. They double as storm shelters, are very energy efficient, work great for extra storage or a game/theater room.
Extra spots for breakers in your breaker box. You never know if you want to add something like a pool, shop, welder etc somewhere and it sucks to have to buy a new breaker box.