If the audiences are everything for web projects, then a successful web site is one that finds a way to engage its audience - i.e. finds ways to grow through reader contributions, comments, ratings, and usage patterns. The same applies to other projects that involve collaboration - especially to the development of online collaborative tools for academics, such as institutional repositories (IRs). The authors of the key text on IRs describe the struggles of engaging the audience very well:
Acquiring the content is slow and laborious work, and at the present time we pay for it with the sweat of our brow, rather than by dipping into our materials budget. It involves - in addition to the seminars in the library - working through lists of academics with research management responsibilities, research journal editors and senior managers, as well as 'common or garden' academics. It requires the organization and tenacity (and thick skin) to lobby powerful committees, to meet academics in their own territory - in departmental meetings, and at lunchtime seminars held by research groups. It requires the hunting down of unorganized self-archived work, and the corralling of it within the institution's managed repository. It requires the capture of author permissions and an awareness of publisher policies on copyright transfer. It involves knowledge of licensing as it applies to self-archived and open access content. ANd most of all, perhaps, it involves the practice of constant repetition of the same message over and over many thousands of times, often to the same people, because the issues are difficult and non-intuitive to academic authors. This is a liaison work, and in a large research university it can easily cost a full-time professional member of staff. (pp. 38-39).
Jones, Richard; Andrew, Theo, and MacColl, John. (2006). The institutional repository. Oxford: Chandos.