The rightmost column goes in pockets, the second rightmost is the contents of my wallet, and everything else lives in my backpack. Full list:

• Right Front Pocket:
  • House key
  • Multitool
  • Wallet
    • Charlie Card (MBTA subway and bus pass)
    • Library card
    • Zipcar card (never used)
    • MetroCard (MTA stored value card)
    • Health savings account card
    • Bank check card
    • Health Insurance card
    • Work credit card
    • Another MetroCard
    • Credit card
    • Dental insurance card
    • List of useful phone numbers, about a year out of date
    • Driver's license
    • Periodic table
    • Printout of MBTA shoes policy transcript and board of health letter.
    • Cash (variable, not pictured)
• Left Front Pocket:
  • Phone
  • Handkerchief
• Left Back Pocket:
  • Work ID badge
• Backpack
  • Toothpaste
  • Toothbrush
  • Dental floss
  • Deodorant
  • Penny whistle
  • Caffeine pills
  • Pens
  • Headphone splitter
  • Grounded/ungrounded AC adapter
  • 1/8" TRS to dual 1/4" TS adapter
  • AC to USB adapter
  • USB to microusb/miniusb/iphone/lightning adapter
  • Superglue
  • Mandolin pick
  • Mandolin strings (there's not enough room in my mandolin case)
  • Umbrella
  • Emergency food x9 (~1300 calories)
  • Earplugs
  • Checkbook

I'm relatively happy with this,but open to suggestions. Is there anything else that would make sense here? The biggest thing I miss is water, but it's heavy enough and available enough that I think I'm happier not carrying it by default.

(Not pictured: clothes, glasses, things I've memorized. My backpack usually also has my laptop and sometimes its charger, but I don't think of these as being in the "always have with me" category.)

Update 2017-09-24: last year I did one of these for Lily: r/EDCL 2/F/MA