Let's revisit the Military Discounts for as many cruise lines that I can think of. I have listed the cruise lines that offer a discount and or OBC (OnBoard Credit). The links below lead you to the descriptions and links if you have to verify beforehand. Some cruise lines do not allow the military discount to be combinable with interline, but I recommend check both just in case.
Atlas
Carnival
Up to $100 OBC, free upgrade and $50 (per person) deposit.
Cunard
Up to $250 OBC (based on length of cruise)
Holland America Cruise Line
$100 OBC and you much verify your status through this link.
MSC
Up to 10% off.
Princess Cruises
Up to $250 OBC
Star Clipper
10% off
NCL - Norwegian Cruise Line
10% off on all cruises. Must register before.
Royal Caribbean and Celebrity
$100 per person discount.
Silversea
On select sailings, 10% off
Comments