A key contemporary trend emerging in big data science is the Quantified Self (QS) - individuals engaged in the deliberate self-tracking of any kind of biological, physical, behavioral, or transactional information as n=1 individuals or in groups. This is giving rise to interesting pools of individual data, group data, and big data which can be interlinked to create a new era of highly-targeted value-specific consumer applications. There are significant opportunities in big data to develop models to support QS data collection, integration, analysis, and use for personal lifestyle and consumption management. There are also opportunities to provide leadership in designing consumer-friendly standards and etiquette regarding the use of personal and collective data. Next-generation QS big data applications and services could include tools for rendering QS data meaningful in behavior change, establishing baselines and variability in objective metrics, applying new kinds of pattern recognition techniques, and aggregating multiple self-tracking data streams from wearable electronics, biosensors, mobile phones, genomic data, and cloud-based services. Potential limitations regarding QS activity need to be considered including consumer non-adoption, data privacy and sharing concerns, the digital divide, ease-of-use, and social acceptance.