The MoH series, however, does deserve credit for acknowledging that the Pacific theater existed, which CoD has yet to do.  

The missions in CoD 3 being more flexible in their approach is encouraging; that's one of the very few things I didn't like about CoD 2 as I prefer my shooters to be more "open."

While I realize it doesn't fall under the realism discussion as far as FPS's go on the Wii Metroid Prime is amazing, both in terms of graphics, gameplay and control.  If you haven't played it yet I highly recommend it.

Battlefield 1942 is somewhat dated (2002), and it's PC-only (though the sequel -- Battlefield 2: Modern Combat -- was available on consoles), but it's a great deal of fun, particularly if you play online with friends. It's a lot more open-ended than CoD or MoH or BiA, as each mission is a huge map with numerous objectives that must be taken (whereas the other games consist of a series of objectives that must be accomplished in linear fashion, with little or no room for deviation). Battlefield is definitely a beer-and-pretzels "buddies" game, though you can play it single-player against the AI-controlled enemies. The bots are decent, particularly in the higher difficulty levels.

Call of Duty appears to have followed in Battlefield's footsteps, at least thematically. Call of Duty 4: Modern Warfare is a modern game, featuring next-gen weapons and technology. Looks good, but definitely not a WWII game.