Kurtis Brown offers a one-page painting guide to Vikings.
Note: the link above is dead, and an email to Kurtis bounced. So I went to the Wayback Machine and retrieved a copy of the page. It is preserved below for posterity.
JD Burgess has a site with dozens of outstanding photos of World War II model airplanes. Each model not only has the traditional 3/4 on photo, but also left, right, rear, above rear, above left … well, you get the picture.
These would make a good painting guide for air war miniature wargamers.
The Uniformes Militares Espa�oles site has extensive color plates of Spanish Uniforms for the years 1800 – 1980.
I know you won’t believe me, but there’s more to painting Austrian Napoleonic uniforms than endless seas of white. You can find more details in the uniform guide here.
There are some nice color plates on this site showing the uniforms of the German states in the 1700s. I don’t know German, but by looking at the plates, I think that they’re all from the Seven Years War. The first page is definitely Frederick the Great and his generals. Someone with more epertise in either the period or in German will have to provide more detail.