A question was raised today on the mailing list: Is there an easy way to add a watermark to a ggplot? There are several options, depending on the type of watermark and the required level of control over the output, add a text label using annotate (th...
Thanks to this great post http://www.imachordata.com/?p=730 we can now put multiple plots on a display with ggplot2. This provides somewhat similar functionality to ‘par(mfrow=c(x,y))’ which would allow multiple plots with the base plot function. gridExtra doesn’t have quite the same level of options as ‘par’, but the syntax is simple. grid.arrange( graph1, graph2, ncol=2 Simple. ‘grid.table’ 
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
