We leave early on the 26th for a couple of weeks in SE Asia (Viet Nam and Cambodia). In an attempt to avoid expensive money changers, we asked our bank to provide us with some spending money. For ~$300 we got 5,600,000 Viet Nam dong!
However, they could not supply us with any Cambodian Riel. Those are going for 4,000 riel / dollar. But dollars are easily accepted even in rural shops, as long as the bills are not torn or damaged. Even a locally obtained Visa is valued in dollars!
Reminds me of our visit to East Berlin the year before the wall fell. Part of the entry process required the visitor to exchange at least US$25 for East German marks. Of course, there was no method of converting any unspent East marks back to dollars or West German marks! I can only assume the same "exchange rate" happened with most any other currency.