See the Pen ECharts Version 3.0 - Scatter Map Brush by Janet Wagner (@WebCodePro) on CodePen.
The library I use the most is ECharts, an open source (BSD 3 license) charting and visualization library from Baidu. I've created quite a few CodePens featuring bar, column, pie, pictorial, line, and other types of charts powered by ECharts. I've also created a number of custom themes for ECharts.
If I ever have the time, I'd like to try out the Clarifai image and video recognition API, Windyty animated weather forecast map API, and Wrld.js 3D mapping API.