72 hour / G.O.O.D. / B.O.B. bags

When I think of a 72 hour /G.O.O.D. (Get out of Dodge) /B.O.B. (Bug Out Bag) Bag, I think of them as a spontaneous 3 day camping trip bag. In fact I generally keep my regular Camping gear with my 72 hour kits so that I would include that gear in an evacuation situation.
What to keep in your bag is really up to you. I would include the things that would make a bare minimum camping trip possible. For instance your gonna want water, food, shelter (tent), a change of clothes / including a sweater or jacket. At a minimum those are the things I would include. Other things that may be helpful would be a first aid kit, sleeping bag, flash light, cooking materials such as matches/ lighter/ or a little propane stove (if you don't include this then make sure the food you've previously packed doesn't require heating and tastes okay straight out of the can and that you can open the can via pop lid or can opener). Once you have the basics squared away think about things that are personal to you like prescriptions, glasses, a deck of cards or book. Here is a link of some the typical equipment in a 72 hour bag: http://lds.about.com/od/preparednessfoodstorage/a/72hour_kit.htm
The thing about these bags is that you have to use them. The supplies and equipment need to be rotated and tested before an emergency. So every 6 months you should plan a 3 day camping trip only using the equipment in your bags, no last minute trips to the store. I like to do this in April and October. Testing your bags is the only way to find out if they are adequate. I did a camping test and decided that while I could cook over an open fire that I'd prefer a camp stove. Also I realized I had forgotten dish soap so had to make do with the bar of soap that I had on hand. You find out that the kids clothes are getting too small and that they really need something different. Or that the shoes you've packed don't have enough tread. Or you might think that fishing really is something you could do to supplement your supplies. So you find out what works and what doesn't, test your bags.
Note: If it is your first test, and you are not familiar with camping either get someone to help you go over your gear and camp with you, or do a backyard camping trip and try not to go into the house for anything. Try to make the test realistic because in an emergency you might not have a house to go to.