Maps of War is a great resource!  The really neat think about the site, as you can read in their Sharing Policy, is that they want you to copy, use, and share their maps, as long as you link back to them. 

I have embedded the maps that interested me the most into my personal blog.  I'd do it here but I don't know how to do it on this blog, so instead I'll provide you with links to them, along with the description on the website.

http://www.mapsofwar.com/ind/march-of-democracy.html - "This map gives us a visual ballet of democracy's march across history as the most popular form of government. From the first ancient republics to the rise of self-governing nations, see the history of democracy: 4,000 years in 90 seconds...!"

http://www.mapsofwar.com/ind/history-of-religion.html  "Our map gives us a brief history of the world's most well-known religions: Christianity, Islam, Hinduism, Buddhism, and Judaism. Selected periods of inter-religious bloodshed are also highlighted. Want to see 5,000 years of religion in 90 seconds? Ready, Set, Go!"

http://www.mapsofwar.com/ind/imperial-history.html   "Who has conquered the Middle East over the course of world events?  See 5,000 years of history in 90-seconds."

I could see using each of these maps as a base to for study units.