Depending on licensing requirements and features you have a few options. SVG is not supported from IE 6 to IE8 so you may find some libraries using canvas to run on IE, and others using VML to run on IE.
Plotkit is a mixed SVG+Canvas library, latest version is a bit outdated (0.9.1 released in 29 August 2006) BSD licensed.
Elycharts is an SVG+VML library (using RaphaelJS under the hood) with a good feature set, interactivity and cool animations. (last version 2.1.3 from December 2010) Mit licensed.
g.raphael is an SVG+VML library (using RaphaelJS, from the same author of RaphaelJS). It is very good for infographics, less good for classical charts. (last version 0.4.1 from 2009) Mit Licensed.
Grafico is again an SVG+VML library (again RaphaelJS based). It has much more chart types than gRaphael or Elycharts but less options/configurability than Elycharts. MIT licensed.
Google Chart Tools provides SVG+VML based charts. It's free to use but I didn't find the complete licensing terms. It also provides an editor (even if it is not easy to find on their site)
D3.js Is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG and CSS.
You also have some commercial option:
ZingChart - This is the only library allowing SVG, VML, canvas and flash in order to support every device out there. It is expensive but very complete.
HighCharts - A very complete SVG+VML library having a very good documentation and a very complete feature set. It has a free for personal use license but it shows a very "strict" interpretation of personal and your own blog may not be considered "personal", that's why I show it under "commercial options".