Sometimes it's prudent to get cash in a foreign currency in advance of a trip. (You may be travelling to a place where credit/debit cards or traveller's cheques are not widely accepted, or where ATMs are rare. Alternatively, your bank/credit cards may work but the associated exchange rates or fees may be unfavourable.)
Banks and bureaux de change differ widely in their exchange rates and fees, with ones located at airports giving notoriously poor rates. In the UK there is a travel money comparison site, travelmoneymax.com, that automatically searches brick-and-mortar and online banks and bureaux de change and displays their rates and fees in a convenient table. You can then select the one closest to you (or one that delivers by mail) that gives the best overall rate.
Is there a similar comparison website for Germany?