[scott_s]

I don't understand your first point; the relationship between two variables is more clear to me from a scatter plot. And that's something else that bothers me about the graph: when I look at a graph with lines, I expect to see trends. But the lines in this graph are actually single data points.

We're on the web, so it would be neat to be able to use the mouse to hover over data points to see labels.

[tokenadult]

Scatterplots are usually necessary to check correlations. See

http://en.wikipedia.org/wiki/Correlation_and_dependence

for a famous set of example scatterplots first designed by a statistician warning students of commonplace errors in interpreting correlation coefficients.