Casual piling of paper-based media during traditional tabletop collaboration is an important practice that helps coordinate task and group interactions. Previous research has shown that the ability to move piles around on a table plays a critical role in accessing and sharing task resources. However, existing casual storage techniques for digital workspaces only provide access to stored items at the periphery of the workspace, potentially compromising collaborative interactions at a digital tabletop display. To address this issue, we introduce storage bins, a mobile storage mechanism that enables access to stored items anywhere in the workspace.We also present an exploratory user study involving the use of mobile and peripheral storage mechanisms on a large, hi-resolution collaborative tabletop display. Findings from this study demonstrate the utility of storage bins and further our understanding of the impact of mobile and peripheral storage mechanisms on collaboration at a tabletop display.