MMM - 2016 This makes a basemap using number of packages.
This script makes a nice looking, publication quality map. It handles projections nicely, and with the exception of bathymetry data, requires no local data.
It is not written as a function, and I'm not sure if that would be useful.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.