I found this site over the weekend that people may find useful. The majority of the photos are merchant ships, but there's a smattering of military vessels too. The biggest pitfall is lack of a decent search engine. I found it easiest to use the "List of Pctures" link to get a PDF file of everything and use the search feature in Acrobat to locate ships of interest. http://www.photoship.co.uk/
There's combat ships--Iowa, Yamato, Bismarck, Hood, Houston, Bayern, Invincible, Moltke, Queen Elizabeth, and so on are all in there. It is predominantly ocean liners, cargo ships, and other merchant vessels though.