The wide use of Web services and scientific workflows has enabled bioinformaticians to reuse experimental resources and streamline data processing in a Web-scale manner. This paper presents a follow-up work of our network analysis on myExperiment, an online scientific workflow repository. The motivation comes from two common questions proposed by bio-scientists: 1) Given services which I plan to use, what are other services usually used together with them? and 2) Given two or more services I plan to use together, can I find an operation chain to connect them based on others' past usage? Aiming to provide a system-level GPS-like support to answer the two questions, we present ServiceMap, a network model established to study the best practice of service use. We propose two approaches over the ServiceMap: association rule mining and relation-aware, cross-workflow searching. Our approaches were validated using the real-life data obtained from the myExperiment repository. Empirical statistics of the constructed service network are also reported. © 2011 IEEE.