Oven cleaner- 1 cup each of washing soda and baking soda, mixed. Sprinkle over the bottom of the oven and spray with water to moisten, spray every few hours to keep moist but let it set over night. In the morning, scrap off. If really tough stuff- add some vinegar and let fizz for 10 mins. Scrub and reapply if needed.
Clean the window with malt vinegar is really good too.