PGF and TikZ - PGF/TikZ is a tandem of languages for producing vector graphics from a geometric/algebraic...
SVGO - Tool for optimizing SVG files
LaTeXDraw - LaTeXDraw is a graphical drawing editor for LaTeX.
Scour - SVG Optimizer / Cleaner
Diagrams Haskell package - Diagrams is a powerful, flexible, declarative domain-specific language for creating vector...
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.