Good lord! Do you people get like 10 miles per gallon with all that junk in the trunk? Seems like many of you are ready for the zombie appocolypse right now. Guess I had better get on the ball.
I only carry:
ice scraper
extra oil
paper towel (or two)
tow strap
first aid/road side "survival" kit
When I'm home in my little valley in Colorado I don't even carry a spare tire with me (donut or otherwise).
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless