Idk about specific items like that. But perhaps my pc and internet access. Like if an emp hit and wiped out all electronics or the internet died...I'd be lost sadly. Cast Iron pans are good too have one of them as well. Also an mp3 player for work/gym, can't imagine using a walkman anymore.
*edit* I'm also 29 and finishing college so maybe I'm not old enough to respect other things like cast iron cookware yet.