R Graph Gallery
There is a gallery of R graphics at http://addictedtor.free.fr/graphiques/index.php.
The nice thing of this gallery is that you can get the sources of all examples, so this can be a good starting point for your own custom graphics in R.
There is a similar page – not so sleek – at http://zoonek2.free.fr/UNIX/48_R/04.html which is a bit more instructive.
None of the pages raise the question whether the presented graphics are useful though …
