PSTricks is a package that allows access to features of PostScript that would not be directly accessible from LaTeX otherwise. It operates in conjunction with dvips so results may not be seen in previewers such as xdvi. The user manual for PSTricks comes in four parts:
There is also a quick reference guide which may be worth a look.
Documentation for the style files and sample outputs can be found in the following documents
Other TeX files that can be tested out include
