jQuery SVG jQuery SVG Well written and documented. Many examples and demonstrations. Supports most of the SVG elements, allows easy access to the elements.
Raphaël — JavaScript Library Raphaeljs / good beginner library; you can easily and quickly do a lot of things with SVG. Well written and documented. Many examples and demos. Extensible architecture. Rich in animation effects.
To convert to PDF: Batik (Java, open source) Inkscape (native binary, open source) Batik will give you more control. With Inkscape, you can use command line options (- IIRC export to PDF)