Byzantine Blog is what it says on the tin, a blog about Byzantium. It is written by Tom and Kim Sawford, with the occasional guest post by Laura Diaz-Arnesto. The blog has been going for over a year and a half now, and so has an extensive backlog of posts on a wide variety of subjects, for example: Byzantine holy relics in Siena in Tuscany, Princess Theophano who married Holy Roman Emperor Otto II, photos of mosaics and other art, the horrific realities of prostitution, the islands of Thasos and Lemnos and a couple of posts on Byzantine medicine, mandrake and wolfsbane. Besides essays and photos the blog also links to various sites, articles, podcasts et cetera that dwell on Byzantine matters.
The Thirty Years War is a website covers that ginormous kerfuffle that consumed Europe in the first half of the 17th Century from the Second Defenestration of Prague to the Peace of Westphalia. It has a handy map with a place locator which will help you tell your Schweidnitz from your Schweinfurt. Here are some other maps, The Religious Situation in Central Europe about 1618, Principal Seats of War, 1618-1660 and Europe in 1648 - Peace of Westphalia.