Other ggplot2 helpers:
MakeBreaks(),
WrapCircular(),
geom_arrow(),
geom_contour2(),
geom_contour_fill(),
geom_label_contour(),
geom_relief(),
geom_streamline(),
guide_colourstrip(),
reverselog_trans(),
scale_divergent,
scale_longitude,
stat_na(),
stat_subset()