If you don't celebrate Christmas or don't have family in town, I'm sure it would be frustrating to have the entire city closed. Here's a list of places that will stay open Christmas day!
Movie Theaters
Starbucks
Eddie's House...Love this restaurant. Get your 50% off gift certificates at http://www.localdines.com/?ref=332
hotel restaurants
Jack in the Box
Arcadia Ice Den
Fogo de Chao
Chompies
Goldman's Deli
Buca di Beppo
C-Fu Gourmet
The Sea Life Aquarium at Arizona Mills Mall
Casinos
Athena Greek Cuisine
McCormick & Schmicks
Wildlife World Zoo and Aquarium
Zoolights
Gingerbread Village at JW Marriott- I just went to see this with my kids yesterday and it is so cool! It weighs 1250 pounds and took so much work I can't even imagine. Definitely worth seeing!