While researching uniforms for the period 1660-1680, I came across a link to a collection at the New York Public Library called the The Vinkhuijzen collection of military uniforms. It's an amazing collection of uniform illustrations going back to the 16th century or even farther in some cases.
The collection is organized by nation and further organized for each nation by date. Getting to exactly the right uniform info I want was easy and browsing through was pure delight. I look forward to spending a lot of time online with this treasure trove.
It's also a great find for sources for my latest project, about which I will blog anon.