The natbib package provides automatic numbering, sorting and formatting of in text citations and bibliographic references in LaTeX. It supports both numeric and author-year citation styles.
The natbib package is the most commonly used package for handling references in LaTeX, and it is very functional, but the more modern biblatex package is also worth a look.
pgf-pie is a LaTeX package for drawing pie charts (and some interesting variants on pie charts) with the PGF/TikZ graphics package.
The examples in this document are from the pgf-pie manual, version 0.2.
The source code for pgf-pie is available at http://code.google.com/p/pgf-pie/.