In case anyone out there is working on a medieval fantasy book or historic medieval fiction, I just stumbled across The Time Traveler's Guide to Medieval England: A Handbook for Visitors to the Fourteenth Century. It is an absolutely AMAZING resource into the culture and customs of the era. For example, what did people wear to bed? When was it appropriate to kiss vs. shake hands in public? Crying was expected in order to get the tax collector off your back. Fascinating stuff, easy reading, and just a treasure of little nitpicky customs, especially with the lower classes, which can really flesh out a world.
Unfortunately, the Kindle version is a little ridiculously priced, but I picked up a copy at Costco today for $9.99. Worth every penny. (the link had it listed at $26.99. It is only $9.69 on Amazon. Or $9.99 at Costco.)