I have changed my org-colview.el so that it is possible to get min, mean
and max values calculated instead of just sums in the table summaries.

I use orgmode as a dayplanner and physical exercise diary.

My exercise data is stored as properties in a year->month->day tree and
it is very nice for med to get an overview of my fastest run or average
heartrate over time with columnview. 

If you developers like it I can make the same changes to
org-colview-xemacs.el and document it in the manual for use in future
releases?

New column operators: min, mean, max, :min, :mean, :max. When prefixed
with ':' use timevalue output format.

Example (I measure speed in min/km):

#+COLUMNS:  %DISTANCE{+;%.1f} %HEARTRATE{mean;%.1f} %MAXHEARTRATE{max} %SPEED{:min} 

Here is the patch: