In-Wall speaker wire and other entertainment system wiring (with lines to a projector mount in the ceiling.).
12 Volt DC electrical wiring in addition to standard AC wiring. That way if you go Solar or Battery, you can keep your electrical systems from doing multiple wasteful conversions.
Ethernet wiring and Cable wiring. While wireless is handy, you need a good wired infrastructure to get your gear in to optimal places. Wired fixed equipment frees up your wireless bandwidth for your portable stuff (and is a bit more future proof since the wired standards are fairly well set).
Drains in the floors of rooms with water service. Much less flood damage when the washer or dishwasher breaks down somehow or a sink gets stopped up with the water forgotten.