This spreadsheet lets you calculate the exchange of one currency into another. While it is not guaranteed to be accurate, and should never be used as a basis for trading or financial planning or other critical calculations, it can be used as a general guide or to learn about currency exchange. It uses the currency exchange rates from Google Finance through the =googlefinance() spreadsheet formula in Google Docs spreadsheets.

You can get your own copy to play with - but here's a preview below: