I'm digging this topic up because I remembered a game that I don't think nearly enough people got their hands on for the PS2.
P.T.O IV
Great naval game, was extremely fun. I also liked how you could switch sides around, such as making the Americans and the Germans team up against the Japanese and the Brits, or however else you felt compelled. Had a lot of fun with this title, just never really saw it around or in stores. Rare title from what I've ascertained, if you come across one for a decent price and still have a PS2, I give this title two big sticky green thumbs up.