Dan put me on to this. We never need create a PowerPoint again. Similar is www.flowofhistory.com by Chris Butler in Illinois. Some great PowerPoints there.
Even though this is a blog (I tell my students to avoid them! Such a hypocrite...) this bloke seems to know what he's doing. From what I can see it's relevant with up-to-date research on a wide range of historical topics. Might be useful for the archaeology unit my year 11s do.