How about a better method of brake cooling after an RTO or even a long taxi – if temps get too high then the only option is to wait and possibly cause a delay. (I think Airbus has fans as an option but it does not come cheap + the usual weight penalty)

Parking sensors for the ground handling vehicles – how often are aircraft damaged because of a misjudgement by a driver. They are fitted to a lot of cars so it should be possible for them to be fitted to catering / de -icing and or fuel trucks.