In case you missed it a couple months ago, Ancestry has rolled out some new military records for it's collection.
You can now search U. S. World War II Navy Muster Rolls (1938-1949). A search will get you information such as service number, rating (rank), date and place of enlistment, and change in status along with the date of the event.
Also available is a collection of U. S. Navy Cruise Books (1918-2009). These are like college year books, except they deal with a navy ship and a particular cruise (or deployment). In them you will find the history of the ship, its ports of call, a list of it's officers and crew. They are actually books and each page has been digitized.