what are the most valuable commodities in a doomsday situation? why?

Food, water, clothing, shelter and fuel, of course. But without weapons and ammunition to stop others from taking what you have, they'll be useless to you in short order.

All you need to know about a true doomsday scenario can be learned by watching Mad Max. "Oh, it'll never get that bad," many will say. Let's hope not. But when the world economy truly collapses, gold and silver won't do much good for you unless you've got the army to protect it.

in a doomsday scenario...the markets fall apart for pretty much everything....society breaks down the stock market certainly doesn't work....simple survival is at risk....commodities???? food, water, shelter are what you should be concentrating on

Depends on what part of the world you are in. US - gas, Vietnam - gold, Far East - rice, Las Vegas in hot summer - water .........etc.

I think we saw proof in the storm in the Northeast, gasoline is where it's at.