The Illustrated History of the Roman Empire website is just that — a neat historical site with loads of pictures and interactive map. There is lots of fodder here for historical wargamers.
The British Museum has a very nice presentation on the art, culture and …. warfare! … of ancient Mesopotamia.
Mike Schubert of the Pretoria Wargames Club has an article on which Essex miniature wargaming figures to use to build armies of obscure near eastern bronze age armies, such as the Mitannians, Canaanites, Later Hebrews and Neo-Hittites.
Here are a set of instructions for building 15mm models of ancient War Galleys from the Jackson Gamers.