I have tables with many columns. I want to create a chart that will allow me
to specify which columns to use for x- and y-axes, preferably with two
pull-down menus. Basically, I want to avoid the present situation where I
create a new chart every time I want to observe the correlation between two
variables.

Another refinement: Sometimes one column will indicate a category for data
points (e.g., column title could be element name; categories: oxygen,
hydrogen, aluminum, calcium, etc.). Can I make the charts to plot one or
more categories as separate data series? (Again, preferably with a pull-down
menu.)

Thanks.