I presented about d3.js at a fronteers meetup in Mechelen.
The talk is a practical d3.js introduction to teach some of d3's fundamentals such as data-joins, scales, axis, labels, ticks, animations...
We started off with a plain SVG representing a chart, refine it, in each iteration touching a new topic to actually update the chart (animate bars and scale) every x minutes.
Take a look at the presentation slides and the demo code.