I am thinking about printing graphs in psql (mainly some histograms). I found so gnuplot is able do very good graphs in console. The one issue is user friendly (with less steps) generating data in good format for this application.
One my idea is introduction new simple output format and execution command with result in this format.
It should work something like
\setenv GNUPLOT_OPTION '......'
SELECT * FROM data
\graw | gnuplot ...
It can be used for any other applications R, ggplot, ..