As collaborative Web-based platforms evolve into service-oriented architectures, they promote composite and user-enriched services. In such platforms, the collaborations typically involve both humans and software services, thus creating highly dynamic and complex interactions. However, today's collaboration tools don't let humans specify different interaction interfaces (services), which can be reused in various collaborations. Furthermore, humans need more ways to indicate their availability and desire to participate in collaborations. The human-provided services (HPS) framework lets people manage their interactions and seamlessly integrate their capabilities into Web-scale workflows as services. It unifies humans and software services and supports ad hoc and process-centric collaborations.