This paper is about the evolution of a system prototype called Pensieve whose goal is to support people's reminiscing practices. A number of technologies exist to manage memory-related content; however, these technologies tend to take a model of memory as information that leads to a focus on capture and access. Pensieve is instead based on reusing memory-laden content people already create in social media services. This idea is supported by theories of autobiographical memory, insights from interviews with eight subjects, and experiences with two prototypes deployed to ten users. These interviews and experiences suggest that people value even simple tools that support reminiscence, as well as providing both design goals and research questions around the design of tools that support people in reminiscing. Categories and Subject Descriptors H.5.2 [Information Interfaces and Presentation (e.g., HCI)]: User Interfaces Keywords reminiscence, memory, social media, personalization