If you've got an oven you think might be tough to clean out, use ammonia.
To remove grease from inside your oven when doing kitchen cleaning, put a small pan of ammonia in the oven in the evening, and then close the oven door. In the morning, remove the pan of ammonia. The grease inside the oven will wipe off very easily.
This is similar to the old water in the microwave trick.
Cleaning Your Oven [Cooking Life Tips]