A mashup is an essential type of interactive web applications that combines data and content from external sources to create entirely new and innovative services. They are an essential characteristic of web 2.0, the second generation of web applications. Using cutting-edge technologies and concepts, the variety of web mashups reaches from simple mapping solutions to complex photo and video service mashups. Exciting genres are electronic commerce mashups, which are used by consumers to gather information about products of find guidance before buying in E-Shops. Currently there exists a broad range of shopping mashups which are combining data from the e-commerce pioneers Amazon and eBay, and many other vendors. This paper initially provides a snapshot of electronic commerce mashups, gained by an extended analysis on electronic commerce mashups. The paper discusses the diverse trends of mashups that have or will have significant relevance on the online shopping sector. Moreover we present selected showcases of useful mashups services for shoppers. Finally the paper identifies major challenges and gives some recommendations both from a technical and social point-of-view.