An interesting hardcover "coffee table" book came out recently titled
Battle At Sea which covers naval warfare from 500 BC to the present day. It's detailed enough for us hardcore types, but I'm sure casual naval enthusiasts will enjoy it too. There are some annoying historical errors, but it has such a large scope and it's so lavishly illustrated I'm not really bothered.
If anyone is interested, I've written a longer review of it for Epinions.com:
http://www.epinions.com/review/Book_...t_473042882180