This video from NOAA is an excellent way to visualize the data on CO2 levels around the world. Watch through to the end to see them extend the graph back through the ice ages, using the Vostok and Epica ice core data:
The full data set is available at NOAA’s site.
This is indeed a fine visualization.
I emailed NOAA saying so and thanking them, and got an email back within a day from the developer Andy Jacobson, whose mail can be found @ NOAA.
The original is this and this is a contacts page.