SVG

SVG is an XML format to describe pictures.
This is great because this is truly multi-platform.

The problem is that thttp://www.blogger.com/img/gl.link.gifhere are very few tools that support SVG.
Ideally, you want to find multi-platform tools to create, edit and display SVG pictures.

Here are some of them:

Sodipodi
Skencil
SVGMaker (PDF to SVG)
The Gimp
Adobe Illustrator
Corel WebDraw

There are other Unix tools that can convert from various format (e.g. pic, fig) to SVG.