That said, in the course of slowly reading _Food in Early Modern Europe_ online through questia, I ran across a description of the exploration process that led to Columbus tripping over the Americas and dramatically changing the way everyone ate in the whole world altho not right away. Sure, I knew about astrolabes and quadrants and I knew about Henry the Navigator. What I did not know about were portolan charts. Actually, I sort of did, but I sure didn't know that's what they were called, and I actually really only knew about the periplus component, not the T and O map that went with it, and I was largely familiar with how they were used. Not really a new idea, after all -- just an expansion of the way people had been navigating the Mediterranean for, oh, millenia.
I mention portolan with great excitement because portolans with a different meaning were a crucial element of Melissa Scott's trilogy, The Roads of Heaven. And there's a lot more overlap than just the name between the two.
Also, I had not realized that some of the agricultural innovation in the same time frame was the result of people reading really old Roman manuscripts and rediscovering old crop rotation technique. *sigh*