Earlier this year I found a great excuse to get familiar with TileMill and MapBox hosting, and wound up creating this map:
The original was derived from a number of data sources, including polygons and rasters of differing cell sizes. I felt the hexagons eliminated the distracting artifacts that left, like areas with right angles, changes in apparent map precision. Adding simple interactivity was also nice – I like the combination of colors (for an overall intuitive sense of TP loading) and tooltips (for precision at a single location).
I also really liked how quickly a map came together with the tools – probably less than two hours, all told, including learning to use TileMill and incorporating suggested revisions.