Put two caps full of vanilla extract in a coffee cup, then place it in the oven at 300 degrees for one hour. Within twenty minutes the whole house smells like Heaven. It's actually a common realtor trick.
Mason jar air freshener - fill a small mason jar about 1/4 full with baking soda, and add 6-8 drops of your favorite essential oil. Punch holes in the lid, and place in any spot that could use some freshening. Every once in a while, give the jar a gentle shake to boost it's air freshening power. Could even paint the jar & lid!