I worked on a data visualization for the 2012 European football championship at Twitter that you can find here.
The visualization shows day-by-day tweets aggregated by country in a streamgraph during the tournament. It also shows tweets per minute for each match of the tournament. Each time series is annotated with extra information for the match.
Interesting reactions happen on Twitter for some matches. For example, for the Greece vs. Germany match you can see how people in Greece cheer on their first goal, but aren’t very cheerful on their second goal, after three consecutive goals from Germany.
There are other interesting patterns and reactions visualized in the tournament, you can explore the visualization at https://euro2012.twitter.com/.