My goal is to make a plot that you can interact with in the browser. Ideally, I would like a well-documented and mature JavaScript plotting library that supports SVG. As far as
One way to this can be seen in the matplotlib gallery.
Basically:
A search yields this: http://www.farinspace.com/top-svg-javascript-libraries-worth-looking-at/
I have used the following libraries for graphs:
There is a HTML5 backend: http://code.google.com/p/mplh5canvas/
If your goal is to take output from a static svg generated by some plotting tool, and turning it into something interactive, then you probably will have to come up with something yourself since the output will most likely be different for every such tool.
However, there are plenty of interactive SVG graph libraries out there, some examples: