Additional examples can be found on the respective help pages of ggplot2. Here, you can find examples of the most important options and scales:
Axis labels and legend titles: http://docs.ggplot2.org/0.9.2.1/labs.html
Scales for x and y axes for discrete values: http://docs.ggplot2.org/current/scale_discrete.html
Scales for x and y axes for continuous values: http://docs.ggplot2.org/current/scale_continuous.html
Theme elements: http://docs.ggplot2.org/current/theme.html