The Krigsspll.dk site offers a very large selection of downloadable flags for the Crusades. They are all very well done.
flags
Amerian Revolution Flags
The Krigsspil site has a large number of downloadable flag images for the American Revolution. The flags are all in .jpg format, so they can be resized to fit whatever figures you use.
Early Crusader Period Flags
Here’s a selection of early crusader period flags.