How about a heater that works!! (I understand this is more difficult than in cars, due to the fact the airplanes are air cooled).
A radio that can replay the last 10 seconds of a transmittion (for those missed clearances).
And a glove box!! When you travel in your car, which stay's pretty level, you need to store things that you don't currently need, but don't want to fall around. However in the plane, which spends lots of time inclined, you have nowhere to put bit and pieces!!!