SVG is an XML based standard for graphics. For more information see the W3C SVG specification or this Wiki.
Good starting points for viewers and examples are Batik (part of Apache Open Source development), and Sun.
Adobe dropped suport for its viewer in January, 2009 but it is still available from their web-site.

The demos on the following pages all require the SVGViewer from Adobe to work in Internet Explorer.
Firefox 3.0.7, Opera 9.64, Flock 1.2.7, Chrome and Safari 4 support SVG in native mode.

Demos

  1. Match
  2. Reverse
  3. Latin Square
  4. Train Game
  5. Jigsaw Puzzle
  6. Save the world!

SVG is not worth the bother for Internet Explorer
Try this.