In many business applications that could be built on the basis of Linked Open Data, the conversion of monetary amounts from one currency to another is a much-needed functionality. For example, hotel prices in a comparison shopping application may have to deal with prices given in differing currencies. While currency conversion APIs exist on the Web, their integration into operations over RDF data is still burdensome and requires proprietary code. In this paper, we propose to integrate currency conversion functionality from open Web APIs into the Linked Open Data (LOD) cloud in a conceptually clean, scalable way that (1) adheres to the LOD design guidelines, (2) removes the need for proprietary code, (3) can be accessed from client-side JavaScript, and (4) works with any standard SPARQL processor that is able to retrieve a RDF representation by dereferencing a resource URI. We argue that our solution serves as a good generic pattern for integrating Web APIs into the LOD cloud, beyond the practical relevance of the concrete implementation.