For the HTML5 version of mapgen2 I added an “icon” feature that adds a hand-drawn icon at the center of each polygon.
This is an easy-to-implement technique that can make the maps look hand drawn. Since the polygons are already spaced evenly but not on a grid, we can reuse the polygon locations for these icons, and it looks like they’re scattered about.
I drew these icons on an iPad using the Concepts app and exported them to SVG. (see exported SVG). Feel free to use these icons in your own projects, 
under the Creative Commons Attribution 4.0 International License.
I was inspired by StarRaven’s Sketchy Cartography Brushes, which were designed for use as Photoshop brushes for people drawing maps by hand. StarRaven also has another set available. I drew my own because I wanted icons that matched the biomes I was using. The biome colors are: