Robotics that can build 3d dimensional building structures in the oceans using nutrients and materials from the ocean. For example, if you could make floating algae bricks, or Coral Bricks and robotically place and combine them. The inspection, maintenance and repair should be fully robotic/automatic also.

Computer cables that light up when you touch them or press a button on them to aid in you tracing where the cable is plugged in. Also, the cables could change brightness or flash based on what type of data is passing through them, or direction of data. Data centers where there are tens of thousands of cables could really benefit greatly.