My brother works for ESPN, which is owned by Disney.
We have gone with him in the past and here are some of the discounts he gets...
-50% off rooms. Unlimited useage. You may book rooms for family and friends, but you have to be in one of the rooms and this is limited to 5 reservations per year.
-He and his wife get a Silver Pass, which allows each passholder and 3 guests to
enter any park worldwide, except for the waterparks.
-He also gets 4 complimentary passes each summer and winter, and can give these to others to use.
-He gets 35% off at the Disney stores, and 20% off at most of the restaurants in DW, but they add an 18% tip when you do that, and you sometimes have to go at off hours.
He also told me that if you are a "Florida" castmember, you can get additional discounts like 50% off to Cirque de Soleil, waterparks, Disney Quest.