[scottmandue]

Living earthquake land I would echo what others have said, 2-4 week supply of:
Food water meds (including pets).
Flashlights, camping gear.
Keep a good pair of shoes or boots next to your bed (lots of broken glass + no light = most injuries in an earthquake are foot injuries).
The gas cutoff thing is a good idea (pretty sure they are mandatory in SoCal).
Make sure everyone knows how to shut off gas/water/electricity.
Some people around here have a generator, best to have an electrician hook it up to your main.
I don't bother with earthquake insurance.

Barter? Toilet paper!