I just use my phone for navigation, and I'm going to get a stereo with bluetooth for hands free calling.
Since mine is a crew cab, I'm also going to add a DVD player in the back for the kiddos as well as a mounted inverter.
Since I'm going to have air bags, I'm adding an air tank and compressor
I would also say that larger brakes could be added to the list. Helps with towing and compensate for the larger tires (and maybe wheels).
I actually put a smaller fuel tank in mine. When I converted to a shortbed, I had to use a shortbed tank.
I didn't see A/C on your list either.