Odds are, in a TEOTWAWKI senario gold and silver will retain some intrinsic value. Particularly if you can get to people who are trying to salvage technology and have a lot of know how. Other than that, I don't see anyone bartering the last of their gas or coffee for gold, but someone who needs something more portable than chickens would have a use for it.

You can also use it for dealing with people who are thinking about when the "situation" will be over.