ggplot2 is a plotting system for R, based on the grammar of graphics,
which tries to take the good parts of base and lattice graphics and
none of the bad parts. It takes care of many of the fiddly details
that make plotting a hassle (like drawing legends) as well as
providing a powerful model of graphics that makes it easy to produce
complex multi-layered graphics.

WWW: http://had.co.nz/ggplot2/