I learned about the Flow of History Website from @shawnmccusker. The 243 readings and flow charts organized by time period and subject, which makes it easy to navigate. Each flow chart provides a one-page overview of a historical topic with a hyper- to the people, 
events, and forces that affected different periods in history.
The Flow of History can be a quick reference tool for specific historical topics, the starting point for deeper research, or integrated to enhance any curriculum. According to Shawn the Flow of History is a “great site with helpful flowcharts that connect ideas in History. Great for breaking free from the textbook.” You can even get the iPad app.