This document presents the research I have undertaken over the last decade. It is both retrospective and prospective in the sense that, although it is obviously focused on my past activities, it also indicates ways for future research. The main topic of my overall research can be summarized as follows: I explore the development of online, open projects, or communities of creation, such as Free, Libre, Open Source Software (FLOSS), from an economics point of view. This means that in addition to renewing the answers to Olson's question about the individual participation to collective action (1965), it questions also the why and how companies participate in this process, renewing Arrow's dilemma (1962) on the incentives to produce innovation and the incentive to disseminate this innovation, and the way people organize themselves to transform participation into concrete pieces of knowledge, being software or encyclopedia articles.