In recent years major web services have opened their systems to outside use through the implementation of public APIs. As a result, web developers have begun to experiment with mashups - software applications that merge separate APIs and data sources into one integrated interface. Because the APIs and data sources are publicly available, in principle anyone can create a mashup. However, because relatively advanced programming languages are required to integrate these APIs, creating a mashup still requires considerable programming expertise. In this paper we share the results of an exploratory study of web developers and their experiences with building mashups. We profile the characteristics of mashup developers, examine the mashups they create, and the reasons they create mashups. From the results of this initial survey we outline a course for future research.