Nowadays, the use of RESTful Web services promotes stateless service interaction and decentralized hypermedia-driven discovery and composition. However, there is a need for models and tools to drive user interaction as well as description, discovery and composition of RESTful services. In this paper, we provide a solution to help users manage, share and discover workflows of RESTful Web services. We annotate RESTful Web services with semantic information, and introduce the notion of composition directory as a Web resource that assists a user in sharing, managing and discovering workflows. Users' composition directories form a decentralized repository of service workflows connected by hypermedia links. We illustrate the benefits of our approach with a typical scenario and show through a set of experiments that the breadth-first search algorithm combined with the exploitation of semantic annotations efficiently answers users' goals by crawling through composition directories.