I am using a map_set call to draw a map, and then using contour to plot some data on top of it.
I want to add a legend to this plot to make it useful, but it would have to be below the entire plot, and everything I've tried creates an overlapping legend over top of my image.
Can you do two plots -- one for your contour map, and another for the colorbar/legend,
using the system variable !P.MULTI to lay them out one above the other? You might also
need to specify YMARGIN keywords appropriately on each plot to keep them from overlapping.
You use pre-written colorbar routines (cbar from JHU or colorbar from Coyote, for example) and use the POSITION keyword to put them exactly where you want them. You can also pass POSITION to MAP_SET to position that where you want it.