We investigate an important interaction that can take place in a ubiquitous computing environment, that of opportunistic browsing, a form of information gathering on the fly. Opportunistic browsing is characterised by being ubiquitous, unintentional and effortless. In this paper, we clarify the concept of opportunistic browsing and place it within a cognitive framework. We further discuss the nature of the interactions that can be triggered by the serendipitous discovery of information through opportunistic browsing and the importance of context-awareness, and we identify important research issues.