In this SD thread, SD members describe how they have been able to get many of these credit card promotions by calling Discover.
- $1 cash back on each transaction for a month ($20 max)
- $1 cash back on each transaction for 3 months ($60 max)
- $50 for spending $1000 or $2000 over 2 months
This is a Your Miles May Vary promotion that requires some luck and knowledge of Discover's customer service. Refer to the thread for the details.