DVC does provide a 10% discount at TDS and at PI. There are a number of discounts at WDW restaurants, tours and other programs available. There is a 10% discount on Unlimited Magic Passes and a 25% discount on cash reservations at DVC resorts- when available.
I prefer not to think of DVC as a discount program other than the great deal we get on accommodations. There are some worthwhile discounts, but IMHO, that is not the reason to join DVC.
There are no discounts on rooms at other WDW resorts or on Hopper passes or AP's thru DVC.