World's Worst Currencies From The Most Unstable Economies

Somalia
Currency: Somali shilling (SOS)
Inflation rate: Nobody knows, but is definitely not low.
Exchange rate: 1,387.77 SOS per US$1
The reason: Everything. When the Somalia collapsed back in 1991, the Central Bank of Somalia and entire banking system collapsed at the same time. The World Bank estimates that as much as 80% of the currency in circulation is forged or reprinted.

Iraq
Currency: The Iraqi Dinar (NID)
Inflation rate: 40.92% in April 2007
Exchange rate: 1,260 NID per US$1
The reason: The war.

North Korea
Currency: North Korean won (KPW)
Inflation rate: Who knows? Prices are set by the central government.
Exchange rate: 2,500 KPW per US$1
The reason: When was it ever right?

Venezuela
Currency: The Bolivar (VEB)
Inflation rate: 19.5% as of May 2007
Exchange rate: Lately, the Bolivar has been trading as high as 4,110 Bolivars per US$1 in the black markets.
The reason: Thanks to President Hugo Chávez’s nationalization campaign, Venezuela’s currency has lost 21 percent of its value since January 2007, the worst performance of all 72 currencies tracked by Bloomberg News.

Zimbabwe
Currency: Zimbabwean dollar (ZWD)
Inflation rate: 3,714% and rising…
Exchange rate: As high as 60,000 ZWD to the US$1
The reason: President Robert Mugabe. His economic mismanagement has led to hyperinflation. According to Boing Boing, ‘the exchange houses in London don't even have a "buy rate" for Zimbabwean money, because the inflation is so rapid that they don't want any more of it.’

Via Foreign Policy