This is a proof of concept for an animation of tag-volume over time. The horizontal rule represents the passage of time, and the vertical rule represents the overall volume of tags at any given point.
Y. Hassan-Montero, and V. Herrero-Solana. Proceedings of Multidisciplinary Information Sciences and Technologies, InSciT2006, Merida, Spain, (25--28 10 2006)
M. Hearst, and D. Rosner. HICSS '08: Proceedings of the Proceedings of the 41st Annual Hawaii International Conference on System Sciences, page 160. Washington, DC, USA, IEEE Computer Society, (2008)