I bumped into yet another old but beautiful visualization challenge this evening. Flowingdata.com's "10 Visualizations for Number of Days to Pay Your Taxes" may have ran in 2009, but it still features some wonderful approaches to data visualization and I had a great time exploring them in some detail, but not before I had made my version of the chart as shown in the picture below.
While exploring, my attention was immediately drawn towards a very unusual "Calendar Interface" designed by Annie Lausier. It was a standout even among some very unique others. I know it would be mighty difficult to replicate it in Excel. For, even with VBA, it will be a tiresome effort. But, I'm willing to give it a couple of hours and see what I can etch out.