For the AP and up to three guests you can get 10% off the regular price of food and nonalcoholic beverages Monday through Friday only during lunch hours only at:
ESPN Club
Sand Trap Bar & Grill (at Bonnet Creek)
Concourse Steakhouse
Trail's End Restaurant
Grand Floridian Cafe
Olivia's Cafe
Kona Cafe
Whispering Canyon
Yacht Club Galley
All Star Cafe (at Wide world of Sports)
Biergarten
Le Cellier
Chef's de France
Coral Reef
Garden Grill
Nine Dragons
Akershus
Marrakesh
Rose & Crown
San Angel Inn
You can also get (seven days a week):
Rainforest Cafe (10% off for breakfast, lunch, & dinner)
Fultons (20% off lunch and 10% off dinner)
Ghirardelli (10% off all the time)
House of Blues (20% prior to 4:00pm and 10% after 4:00pm)
Planet Hollywood (10% all the time)
Portobello Yacht Club (20% off lunch and 10% off dinner)
Wolfgang Puck Cafe-West Side (20% off lunch and 10% off dinner)
Wolfgang Puck Express Market Place (10% breakfast, lunch, & dinner)
It's not listed in my 2007 Passholder booklet, but I believe that Yak & Yeti in AK also offer an AP discount. I hadn't noticed until I started looking at it just now that MGM and MK restaurants do not have any restaurants listed for AP discounts.