Today, people are often members of several online communities, leaving their footprints scattered across cyberspace in the form of local reputations. Collecting these reputation data to build a global reputation becomes increasingly necessary. This article proposes a new perspective on the topic of sharing reputation data across online communities. We discuss the notion of global reputation, propose a taxonomy for reputation data sharing and use it to briefly study the related literature, and identify and discuss some of the key challenges towards reputation data sharing. To encourage future research, we also propose a conceptual model for global personalized reputation management.