o2 Inklusivpaket SIM (100 free minutes / 100 free SMS per month) for effective 1.33€ per month.

• UPDATE: Offer over!!!
• 100 free minutes apply to calls to German landline and to the German mobile networks of T-Mobile, Vodafone, E-Plus and O2. 
• When free minutes or free SMS limit of the month is exceeded, price is 0.29€ per minute or 0.19€ per SMS
• Get back the connection fee of 30€ by sending a SMS with text "AP frei" (without quotes) to 8362
• Contract period: 24 months
• Effective contract price: 1.33€ per month (10€ per month - 5€ discount per month - 3.67€ money transferred back to your bank account per month)
• No other additional charges.

Here is the deal