I mostly design small, self-contained visualizations for small businesses. The data I get and the level of "visualization design" I have to do depend a lot on the client.

I have worked among others with data on local traffic (congestion and travel times), interaction between players on a field during a game, computing performance, some internal manufacturing metrics. I think there's quite a few areas where people want dashboards that are both fancy looking and informative, either for their clients or for themselves.

Some people just have a vague notion of some data they somehow want to display, others have quite precise demands (typically: "I've seen this d3 example and I want the same with this and that specific interaction/effect added.")