See in action http://bl.ocks.org/3766585
This simple column chart shows how to handle negative values on the y axis. It handles ordinal values for the X axis only.
I started with this gist from Mike Bostock: https://gist.github.com/2368837 see it on blocks: http://bl.ocks.org/2368837
borrowed a bit from the histogram example in D3: https://github.com/mbostock/d3/tree/master/examples/histogram
and used the reusable chart convention from: http://bost.ocks.org/mike/chart/
