Int. J. Environ. Res. Public Health 2009, 6 516 (http://www.healthgrades.com) and Physician Reports (http://www.physicianreports.com). There may also be reputational aspects to doctor participation in health social network physician Q&A. Figure 15. Examples of publicly-available patient reviews of physicians (Yelp). 3.4. The Advent of Health Social Networks as Influence Entities Peer-based health networks could be poised to become a powerful member of the health care ecosystem with an expanding role, possibly having influence in policy, ethics, regulation, research and finance. It will be interesting to see how health social network identity develops and is expressed since a health social network is simultaneously an aggregation of individuals and an institution with its own leadership, goals and agenda. In other sectors, social networks have sought to maintain neutrality by “only providing the platform,” for example peer-to-peer finance sites like Prosper (http://www.prosper.com). It is too early to forecast what will happen with health social networks, but PatientsLikeMe as the flagship example has an on-site research staff and appears to be quite involved in administering and orchestrating the patient community, with a collaborative stance towards traditional medicine. Internet-expert Clay Shirky notes the progressive stages of social network activity which seem to be unfolding in lockstep in health social networks: initially sharing, then collaborating, and finally organizing for collective production and collective action (http://www.herecomeseverybody.org). In addition to external collective action, the internal peer support of health social networks could evolve into positive-impact peer pressure, for example, members competing to lower key biomarker scores like cholesterol and blood pressure, using third- party test uploads from LabCorp to measure and validate the results. Health social networks could develop into large-scale online aggregated communities with market power, providing visibility into demanded research and remedies and directing and funding research priorities. One future example could be the CureTogether migraine community raising $50,000 in crowd-sourced funding, reviewing and approving grant applications, open-sourcing the research findings on their website and developing and testing remedies in patient-run clinical trials. Health social networks could become a key quantitative indicator and independent barometer of demand for medical research, a useful input to the research agenda-setting of governmental funding bodies such as the National Science Foundation (NSF) in the U.S., pharmaceutical companies and academia.