In industry, the Fourth Industrial Revolution is transforming the roles of people, technology and work on the shop floor. Despite ongoing strides towards automation, people are anticipated to remain integral contributors in future manufacturing. Where full automation is ineffective or infeasible, Operator Assistance Systems (OAS) can augment workers’ cognitive or physical capabilities. We frame OAS as a subset of Human-Computer Interaction (HCI) systems designed for the purpose of workforce augmentation in production systems. However, while OAS are anticipated to address key needs in industry, a challenge for both OAS researchers and industrial practitioners is to identify the most promising applications of OAS and justify them from a value-added perspective. This contribution addresses this challenge by presenting a systematic literature review of 2,928 papers, revealing (a) 11 application areas for OAS; and (b) 12 approaches for assessing the value-added of OAS. Moreover, we discuss implications for OAS, with a particular focus on integrating OAS in industry.