It's Hubby's favorite restaurant, too, and he gets to eat there on his birthday this year! Lucky duck!
Anyway, although Fulton's no longer participates in the DDP (they did when we went of August 2004), you can get a small discount if you are an AP holder. From allears:
Fulton's Crab House at Downtown Disney's Pleasure Island - 20% discount off the regular price (excluding tax and gratuity) of food and beverages daily during lunch (seated by 3:30 pm) and 10% discount off the regular price (excluding applicable tax and gratuity) of food and beverage during dinner. Valid for Passholder and up to 3 guests. Advance dining reservations are available by calling 407-934-BOAT(2628) or 407-WDW-DINE (939-3463).
Hope that helps and enjoy!