SVG tools

Official Resources:
http://www.svgi.org/
An almost comprehensive list of vector drawing programs(actually some 3d software is included as well):
http://www.maa.org/editorial/mathgames/mathgames_08_01_05.html

Free Editors:
Inkscape(most popular open source one): Besides svg, it can save file as .ps, .eps ... It also allows users to export file to .PNG(just .png, not .jpeg or .gif).
yED: a good graph editor which can automatically beautify line layout in the graph.

Standalone Viewer:
Batik Squiggle(pure Java): zoom in/out, transform... Can export .svg to .png, .jpeg and .gif.

Convertor :
ImageMagick: a powerful command line tool which provides functionalities of conversion, edition and composition. .svg can be converted to .jpg, .gif, .eps, ...

Conversion of .svg to .eps: Inkscape provides a better result than ImageMagick.