Matplotlib's new default colormaps as a style file for ArcMap/ArcGIS.
For more background and an informational talk, see this page.
This style file uses the values in https://github.com/BIDS/colormap/blob/master/colormaps.py to build color ramps for ArcGIS.
I used 15 evenly-spaced points along the 256-value colormaps, and assembled them as multi-part algorithmic color ramps using the CIE Lab algorithm. Here's how they turned out:
Adding the styles to ArcMap 10.x
Step 1. Go to Customize -> Style Manager...
Step 2. Then "Styles..."
Step 3. Then "Add Style to List..."
Step 4. Select the matplotlib.style file and add it.