I personally love Tea Tree Oil.  I have it in my cleansers and my diffusers and I even put it in the bath with epsom salts.  It is really great stuff.  And if you have a small bottle of distilled water and add a few drops of the tea tree oil the essential oil then it makes for a great spray to keep things fresh or to even clean your cupboards with.  Add a little to vinegar and you will make a great disinfectant!