I worked on a data visualization for the 2012 European football champioship at Twitter that you can find here.
The visualization shows day-by-day data aggregated by country but also shows tweets per minute for each match of the tournament.
I made some tweaks to the JavaScript InfoVis Toolkit to create the StreamGraph visualization. During the process I made some mistakes that ended up in curious pseudo-visualizations like this ScribbleGraph:
Or like this ScatteredFeatherGraph:
Or even this Windows solitaire tribute graph:
I’m thinking on writing a paper about these (not).