Multi-User Piles Across Space

We introduce Multi-User Piles Across Space, a technique that allows co-located individuals with PDAs to share and organize information items (e.g., photos, text, sound clips, etc.) by placing these items in shared, imaginary off-screen piles. This technique relies on human capacities to remember spatial layouts, and allows small co-located groups with limited screen real estate to collaboratively manage information. Each participant can use their PDA's stylus to flick information to shared off-screen piles and view their contents. Connections are implemented through ad hoc WiFi. Optimistic concurrency control provides long term data consistency. We also describe an extension that allows PDA owners to transfer information items and piles to and from a tabletop display.