There is a tremendous amount of web content available today, but it is not always in a form that supports end-users' needs. In many cases, all of the data and services needed to accomplish a goal already exist, but are not in a form amenable to an end-user. To address this problem, we have developed an end-user programming tool called Marmite, which lets end-users create so-called mashups that repurpose and combine existing web content and services. In this paper, we present the design, implementation, and evaluation of Marmite. An informal user study found that programmers and some spreadsheet users had little difficulty using the system.