Using your grill like an oven is a great way to be able to make all the recipes than call for the oven in the summer time. You can still make your recipes and not heat up the whole house doing it.
Chow tells us that mostly you need to know the temperature and solves the problem by drilling a hole in the grill and bolting an oven thermometer inside it. They also suggest using a cast iron dutch oven because they are pretty much indestructible and it is hard to burn things in them. Read the article for more hints and tips and see if using your grill for an oven is something you would like to do.