As technology continues to shape our interactions in both personal and educational contexts, the exploration of how computer-mediated communication (CMC) may impact the development of second language writing skills has received greater interest. While a growing body of research has investigated potential applications of this technology within second language (L2) classrooms, the voluntary writing practices of L2 writers--where and what they choose to write outside of academic domains--are relatively uncharted as yet. This review of the literature seeks to identify the many CMC contexts in which L2 writers situate themselves, their purposes for engaging these online audiences, and the social roles or identities that emerge through their chosen writing activities. Previous studies indicate that social media platforms and other online communities indeed promote learners' experimentation with identity, group membership, and language with apparent gains in writer confidence and motivation; however, establishing a clear link between CMC and literacy development, as well as determining how computer-based writing can be meaningfully integrated into academic settings, remain directions for future research.