evkarem We do the baking soda and vinegar method. It's a great way to use up your old baking soda after it's done its job in your fridge or freezer. Don't throw it out; it's still useful! Just because it can't absorb any more odor, it still reacts with vinegar.
http://thegoodhuman.com/2007/03/21/naturally-unclog-drain-with-vinegar/