Free drawing software for Windows, Mac OS X, and Linux
Dia Diagram Editor is free Open Source drawing software for Windows, Mac OS X and Linux. Dia supports more than 30 different diagram types like flowcharts, network diagrams, database models. More than a thousand readymade objects help to draw professional diagrams. Dia can read and write a number of different raster and vector image formats. Software developers and database specialists can use Dia as a CASE tool to generate code skeletons from their drawings. Dia can be scripted and extended using Python.
Synfig is a powerful, industrial-strength vector-based 2D animation software package, designed from the ground-up for producing feature-film quality 2D animation with fewer people and resources.
Vector drawing program for LaTeX using PSTricks
LaTeXDraw is a graphical drawing editor for LaTeX. LaTeXDraw can be used to 1) generate PSTricks code; 2) directly create PDF or PS pictures. LaTeXDraw is developped in Java and thus runs on top of Linux, Windows, and Mac OS X.