In this paper, we consider the problems of group discussions and collaborative decision-making, where one or more of the participants are using restrictive interfaces such as mobile phones or PDAs. We suggest possible solutions to some of these problems and present MAVis (Mobile Argumentation Visualizer), a web-based interface built upon upon a balance-beam visual metaphor. We report on user experiences of interacting with the visual metaphor, and on the challenges of transferring this to a multi-user environment supporting mobile devices.