I've become all about redundancy on the basics - in the city that emphasizes cash and flashlights - so I've got these items in winter coats, purses, wallet, etc. and I often have several of these things with me. Below is off the top of my head so it's a partial list. And it will vary somewhat by season.

Winter coats:

Cash
LED light (e-Pico and/or Petzl Zipka)
Bic lighter
Knife (Doug's little MK-5)
for dog walks after dark I also carry a Surefire or Fenix TK35
business cards (they burn and can be written on)
gallon plastic bags (used primarily for dog doo but multi-use)

House key Lanyard (paracord 550):

Pen (All-Weather Trekker Pen from BPTS)
e-Pico light
Whistle

Car key fob:

Firesteel wrapped in blaze orange duct tape & scraper
paracord thingamijig - blaze orange
whistle - blaze orange
mini pry bar - wrapped in blaze orange 550 paracord

Wallet

Doug's MK-5
Firesteel (miniature)

Dog walking shoulder bag

moleskine notebook (mini)
space pen refill
business cards
extra leash
gallon plastic "storage" bags
cash
pepper spray

Purse(s):

Petzl Zipka
Bic lighter
Stormproof matches
Kleenex packet
cash
cotton bandanna
my wallet's stuff
AM-FM radio

Rucksack (walks around the 'hood or on the Mall):

lots of the above stuff plus...
water
First-Aid
Titanium Evernew Sierra Cup (aka: dog's water bowl)
MoJo bars (2)
AMK Heatsheets
AM-FM radio

Daypack (hikes in the metro area - such as the C&O Canal):

Esbit stove and fuel tabs (during winter)
Tea bags (Earl Grey double bergamot + Liptons Cup o' Soup)
chemical hand warmers (during winter)
Becker Necker (wrapped in fluorescent green paracord 550)
AMK Heatsheets
Leatherman Micra
AM-FM radio

Bike Rack bag w/panniers and handlebar bag:

First-Aid
Becker Necker
water
lights
extra dog leash
PSK (Doug's)
AMK Heatsheets
(plus I always ride with rucksack or daypack)

Honda Element

Way too much to list. My dog (couple days food for her is packed) and I could comfortably camp for a weekend in it, at all times.