Web 2.0 affordances have changed the landscape of technology use for learning, knowledge construction, and collaboration important for K-12 learner literacy. This chapter introduces web 2.0 technologies, including folksonomy, collaborative writing tools such as wikis, and weblogging, as cognitive tools that can support learning of content, metacognitive activity, and self-regulation (SR) at the K-12 level. Recent conceptual and empirical research is reviewed to support the use of these technologies. Application scenarios are provided to elaborate on how the technologies can be incorporated into teaching. Design and implementation implications, and a discussion of issues and challenges are included throughout for teachers, practitioners, and researchers interested in adopting these new media in the school setting.