RaphaelJS is a javascript library allowing you to work with vector graphics on your site with a minimum on code.
It’s cross-browser and is supporting Firefox 3.0+, Safari 3.0+, Chrome 5.0+, Opera 9.5+ and Internet Explorer 6.0+.
You can find some really cool demo’s on their website.
For example: a reflection effect for images, text-rotation, some nice graph’s, a polar clock, a vector image of a tiger and last but not least a 3D shooter example.