The U.K. energy consumption guide
I'm a sucker for anything cute and bubbly, and the U.K. Energy Consumption Guide created by Epiphany is no exception. It combines a vertical scrolling site with a lot of data visualization about different types of fuel and how they've been used historically. Most of the charts are solid and the interaction adds an even higher level of clarity and understanding.
While I like this circle packing chart, I'm sure there will be doubters. It's very similar to McCandless' natural gas visualization that received a lot of flack. But generally speaking, anything that is engaging and welcoming garners a little extra time from the visitor to make sense of it.