Surprise, surprise. Hollywood has it wrong.
Here’s a documentary showing how historical swordfights really happened.
Medieval
Building A Medieval Roadhouse
Terrain Thralls has an illustrated tutorial on making a half-timbered, two story roadhouse. The end result is beautiful, and would be useful in a wide variety of settings.
Medieval and Renaissance Flags For Download
The Krigsspil site has a huge number of medieval and renaissance flags available for downloading.
Flags For 14th, 15th and 16th Century European Armies
Vexillia has a selection of free flags for various European armies from the 14th, 15th and 16th centuries. These include 100 Years War, Wars of the Roses, as well as Spanish, Swiss, Landsnechts, Savoyed, Venetian and Imperialist.
Look in the right hand sidebar on the page for the links.
Making Simple Medieval Wargames Buildings
Terragenesis offers a great photo tutorial for making medieval wargames buildings.