plotting sd bars
Finally, I've found some time to plot sd bars (tnx to @edwindj for sd calculations):

This is together with mean bars. It's also possible to plot only the sd bars. See demo script https://github.com/mtennekes/tabplot/blob/master/test/test_numMode.R to experiment for yourself.
Let me know which mode you like best.
Nice! Seems like a real improvement upon just plotting the mean of numerical values.
Any suggestion which default setting to use for numMode?
Small downside of using sd bars, is that the fraction of missing values is not shown. However, one should be able to see this indirectly by the increase of sd.
My choice would be "mb-sdb-ml" as default.
However changing default behavior is not very user friendly: maybe we should generate a message/warning when numMode is not specified, similar to ggplot2 saying: choosing numMode = mb-sdb-ml.