This paper situates NIME practice with respect to models of social interaction among human agents. It argues that the conventional model of composer-performer-listener, and the underlying mid-20th century metaphor of music as communication upon which it relies, cannot reflect the richness of interaction and possibility afforded by interactive digital technologies. Building on Paul Lansky's vision of an expanded and dynamic social network, an alternative, ecological view of music-making is presented, in which meaning emerges not from "messages" communicated between individuals, but instead from the "noise" that arises through the uncertainty in their interactions. However, in our tendency in NIME to collapse the various roles in this network into a single individual, we place the increased potential afforded by digital systems at risk. Using examples from the author's NIME practices, the paper uses a practice-based methodology to describe approaches to designing instruments that respond to the technologies that form the interfaces of the network, which can include scores and stylistic conventions. In doing so, the paper demonstrates that a repertoire—a seemingly anachronistic concept—and a corresponding repertoire-driven approach to creating NIMEs can in fact be a catalyst for invention and creativity.