Dive Tortola, BVI has these offers:
Pay for 9 divers with accommodation and the 10th stays and dives free.
Pay for 5 days diving and get 1 day free.
Email them for more details: diving@divetortola.com

Low Key Watersports, St. John has 10% off with this coupon

Chris Sawyer Diving Center, St. Thomas, USVI also offers 10% off internet specials. More info here: Chris Sawyer Diving Center