The document discusses how the Dopplr travel app shares data and integrates with other platforms and services in order to maximize possibilities for reuse. It covers topics like sharing travel data through feeds, using OpenID for user identity, importing social networks, delegating authority through OAuth, creating widgets/plugins for sites like Facebook, and using Amazon Web Services for hosting. The goal is to design Dopplr as a "small piece loosely joined" that builds upon existing internet platforms and technologies.