This is an interactive tool from Harvard and MIT that enables users to visualize a country's total trade, track how it changes over time and explore growth opportunities for more than a hundred countries worldwide. Apparently, this has been around for a few years and it's quite impressive. There's an enormous amount of data here that's very well organized and is easy to navigate. Highly recommended.
With multiple APIs and a web app that makes it easy to upload data, Plot.ly has become one of the most interesting data viz platforms on the web. Here are some of the best Plot.ly graphs of the year as curated by Plot.ly. These are all interactives and it's definitely worth clicking around to explore.
Nice collection of Data Viz tools and resources that came out of 2014. This is a MUST READ article for anyone interested in data visualization.