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.
Terragenesis offers a great photo tutorial for making medieval wargames buildings.
Here’s a video with photos from our group’s recent game of SAGA Crusades, featuring 60mm! figures. All of the figures were painted by Brad N.
The game was Saracens versus Crusaders. The Crusaders got the upper hand early, severely damaging several Saracen units. But the the dice went against them and the Saracens were able to kill the Warlords of both the Norman and Spanish contintents.
The DMMapp (Digitized Medieval Manuscripts App) links to more than 300 libraries in the world. Each one of these contains medieval manuscripts that can be browsed for free.
Here’s a nice photo essay on making a medieval town building.