CurrCon

This extension allows you to convert between 30 currencies without leaving your current tab, see the description for moreFIXES IN RECENT RELEASES
1.0.6:
Minified the JS and HTML
Minor UI changes

Added Feature in 1.0.5:
Adds comma every three characters to separate thousandths for the output making it clearer to read

Fixes in 1.0.4:
Can't convert currencies of the same kind
Changed the way the conversion is determined
More unique name than 'Currency Converter'

DESCRIPTION
This currency converter supports a large amount of currencies; Australian Dollar, Bulgarian Lev, Brazilian Real, Canadian Dollar, Swiss Franc, Chinese Yuan Renminbi, Czech Republic Koruna, Danish Krone, Euro, British Pound Sterling, Hong Kong Dollar, Croatian Kuna, Hungarian Forint, Indonesian Rupiah, Israeli New Sheqel, Indian Rupee, Japanese Yen, South Korean Won, Mexican Peso, Malaysian Ringgit, New Zealand Dollar, Omani Rial, Norwegian Krone, Philippine Peso, Russian Ruble, Swedish Krona, Singapore Dollar, Thailand Baht, Turkish Lira, United States Dollar and the South African Rand.

Combine that with its ease of use and you are a set to go.