I guess it's just that Appalachian wisdom you got, but I think you got most of the stuff you need in there. Instead of the air duster, for the outside of a newly acquired dusty system, I take it out in the garage and use the air compressor. hehe, more power. I keep a some toothbrushes, the vital alcohol, cheap, stiff paper-towels (for nintendo connector cleaning), precision and normal screwdrivers, my gamers screwdriver set ( with torx and security bits), and thats about all I can think of.
Brad