If I'm just going out, I carry my wallet, keys, cellphone, and chapstick (Canada FTW)

If I take my backpack with me, which I usually do when I am taking transit instead of driving, I would probably also have water, an mp3 player (fuck iPods), my leatherman knife/tool/drillbits, and some other random shit I'm likely never to need.

And crack. You never want to get caught without some rock in Vancouver. I think we are required by law to fire up a stem at least once a week.