Just passing along some interesting info:
http://www.activistpost.com/2011/07/alternative-markets-barter-systems-and.html

Excerpt:
"We agreed that the military, even honorable oath keeping men and women, would feel compelled to participate in a martial law scenario if there was no alternative in place for Americans to utilize during a breakdown. If we were tearing each other apart for food and water, the DHS, FEMA, and NORTHCOM, would have the perfect rationalization for complete lock-down, and a lot of the troops would go along with it."