TikZ and PGF are TeX packages for creating graphics programmatically. TikZ is build on top of PGF and allows you to create sophisticated graphics in a rather intuitive and easy manner.
Disclaimer: This site is not the official home of TikZ and PGF. Consult the Sourceforge project page for releases, support and bug reports.
Track the development of TikZ and PGF.
TikZiT is a cross-platform application that allows the creation and modification of TeX diagrams written using the pgf/TikZ macro library. It is especially geared toward rapidly creating "dot"-diagrams for use in academic papers.
QtiPlot is a program for two- and three-dimensional graphical presentation of data sets and for data analysis.
This package provides a macro for drawing trees with TikZ using the easy syntax of Alexis Dimitriadis' Qtree. It improves on TikZ's standard tree-drawing facility by laying out tree nodes without collisions.
A Java AWT/Swing Graphics drop-in replacement that renders to the TikZ/PGF (LA)TEX language.