[R] [newbie] how to represent very skewed spatial data?

[Tom Roche]

What are good ways to (automatedly) plot (or othewise present) spatial data that is very skewed? E.g.

http://tinyurl.com/dn2VerySkewedSpatialData

produced with fields:image.plot. There are obviously outliers :-) which may or may not be "for real." At an exploratory stage in the investigation, I don't want to prejudge, I just want to show both

1 where the outliers are. This is not such a problem in the plot
  shown, but is often a problem in others, where the outliers are
  just a few pixels/gridcells. I could highlight them by, e.g.,

* importing the output into an editable format
* drawing circles around the outliers
* exporting back to distributable format (e.g., PDF)

  but that would be Real Work; automated solution much preferred!

2 how the rest of the data is distributed. Normally I'd do this with a
  quantile plot, and in fact that's what I'm doing. The jumble at the
  bottom of the legend are the quantiles overwriting each other :-)

Hence my appeal to the vast experience of the group regarding Best Practice, not least because I can't believe I'm the first person to have this problem.

TIA, Tom Roche <Tom_Roche at pobox.com>