This might be a tough one, but one I think would be both extremely useful and interesting.
Conveyors are great for filling up storage boxes with all the raw materials we need.
Having a way to sort those materials, preferably automatically would be golden.

Some manner of small device, with a single "input" connector, and a number of "output" connectors that can be assigned a Material would be fantastic.

This could then be inserted into a Conveyor line, and sift the items coming in to different containers going out - allowing us to designate separate containers for different materials.