Which of Your Gadgets Is Worth Fighting for?

So some ass-hat has been on a mugging spree around Columbia University, holding up students for their iPhones—exclusively for their iPhones—and it got me thinking. I'd gladly hand over just about anything on me—my watch, laptop, wallet—everything but my phone. I mean, it's my access to my entire digital existence, I'm not giving that up without a fight. How about you? What's the one device you carry that you won't (not can't, won't) do without?

Side note: If you see the worthless bag of dicks pictured above in the NYC area, call the police...just not on your iPhone.