Inkscape is vector graphics software for creating icons, illustrations, logos, diagrams, maps and web graphics. It's cross-platform, extremely feature-rich yet simple to use, and extendable. Users therefore include design professionals as well as hobbyists. It's engineered around the open and standard SVG (Scalable Vector Graphics) format. Its sophisticated drawing tools easily match up to Adobe Illustrator, CorelDRAW and Xara Xtreme. Inkscape also can import and export to AI, Encapsulated/Posts
BirdFont is a font editor which allows creating vector graphics and exporting them as TTF, EOT & SVG fonts. It simplifies glyph creation through a snap grid, or allows to trace them from background images.
abcm2ps is a command-line program that converts ABC music notation files to sheet music in PostScript or SVG format.
EasyABC is an open source ABC editor for Windows, OSX and Linux. It uses abcm2ps and abcMIDI for typesetting the score and playing the music.
wxSVG is C++ library to for Scalable Vector Graphic (SVG) files. It can create, manipulate and render them using the wxWidgets toolkit.