Nobelcom has cards for calling Germany that are as little as 2.3c per minute (1.3c + a 1c surcharge if you use an 800 number--check if your hotel allows free local calling and you can save):

http://www.nobelcom.com/phone-cards/...tes-1-108.html

The differences between the cards on the page have to do with rounding and maintenance charges. A card with 4 minute rounding will charge you for 8 minutes of time if you make a 5 minute call.

Note there's also a tab on that page for cards with connection fees, which are even cheaper per minute. But those only make sense if you make really long calls.

There's also a link on that page to a different set of cards that are slightly cheaper to mobile phones (the rates on that page are for landlines, and mobile phones can be significantly more expensive to call).