We present two projects that facilitate collective music creativity over networks. One system is a participative social music system on mobile devices. The other is a collaborative music mixing environment that adheres to the Creative Commons license [1]. We discuss how network and community infrastructures affect the creative musical process, and the implications for artists creating new content for these formats. The projects described are real-world examples of collaborative systems as musical works. Categories and Subject Descriptors H.5.3 [Information Interfaces and Presentation]: Group and Organization Interfaces---Collaborative computing; H.5.5 [Information Interfaces and Presentation]: Sound and Music Computing---Systems General Terms: Design, Experimentation. Keywords Interactive music, online communities, peer-to-peer, sensor interfaces, social computing.