The fast growth of social media is moving on and new records are continually published from the world of Facebook, Twitter & Co. The big success of several social media services leads to its strong use by the internet community to communicate, collaborate and interact in private and professional life. Many companies have already realized the high potential of the social web and are successfully applying such innovative services to achieve a higher efficiency by optimizing internal and external processes. Social web services are especially suited for marketing and communication activities as strong tool to interact with customers and other stakeholders. However, many companies haven´t yet realized the extensive power of the web community. Thus, many marketing and communication campaigns failed right from the beginning or in the worst case even caused negative effects on them. This paper discusses different strategies how to use the social web for business and points out the potential pitfalls and risks based on representative case studies. The selected cases illustrate potential negative consequences like image damage or financial loss and the dynamics within the web community. Finally, crucial recommendations for companies are presented to avoid negative side-effects of modern marketing strategies.