Studio McVey has a short tutorial on painting camouflage patterns on a pair of pants.
Painting Guides
Viking Painting Guide
Crusader Miniatures has a painting guide for Vikings.
World War II Painting Guides
Artizan Designs has a page with very good painting guides for a wide variety of World War II Uniforms.
Armies of Finland 1783 – 1811
The New York Public Library has a large collection of color plates of the armies of Finland in the 18th and early 19th centuries.
Uniforms of Norway and Sweden 1500 – 1909
Here’s a large selection of color plates of the uniforms of Norway and Sweden from 1500 – 1909.