Health-related research is increasingly drawing on novel sources of online data, such as crowdsourced information about disease outbreaks, consumer-supplied information provided to health or wellness Web sites, Internet search queries about personal health, and social network postings that identify health behaviors. We offer examples of online sources and their uses, identify ethical and policy issues they generate, and formulate key questions for future discussion and investigation. Further work in this area will require cross-disciplinary collaboration to develop ethics and policy guidance for the ethical use of these novel data sources in health-related research. (Am J Public Health. Published online ahead of print October 18, 2012: e1-e6. doi:10.2105/AJPH.2012.300813).