Some quick links to some useful exchange rate tools:
ONADA
Excellent currency tool for average and historic exchange rates (http://www.oanda.com/currency/average). Onada also offer real-time exchange rates and fx currency trading services.
XE
Currency Comparion site – with a well formatted live currency table on the home screen, you can get quickly get the latest comparable currency rates.
XE also offer a historic rate service across most major international currencies.
There is also a very useful application for Apple devices – great for making quick currency calculations on the move, for work and leisure.