Massachusetts Historical Society online maps include local towns and counties dating from 1637-1809 and iconic printed maps of Massachusetts and Boston.
For local maps, the Boston Planning and Development Agency webpage has maps and aerial photographs.
You may want to view the Myra Kraft Open Classroom presentations on Youtube
U.S. Census Bureau Maps and Cartographic Materials webpage provides a library of historical and thematic maps.
Worldmapper: The World as You've Never Seen It has maps showing areas of interest--not country boundaries. Looking for a map showing the distribution of wealth, income, food, housing?