I found quite a bit:
- One that draws shapes (http://www.dashingd3js.com/using-json-to-simplify-code)
- And the other that draws a graph (http://bl.ocks.org/mbostock/4062045)
- A helpful article that explains data transition with (out) AJAX (http://empire5.com/development/d3-js-dynamic-bar-graphing-with-transitions-and-json/)
- Also, check out this question, How would d3.js difference chart example work with json data?
I hope this helps!