Here at my house, between the two cats and four people, every once in a while I will notice a urine odor either near the litter box or in one of the bathrooms. I have tried just about everything I could think of to get rid of the odor to no avail. Then I read somewhere about a very cheap, easy, effective and quick way to get rid of that urine smell.
All you need is an empty spray bottle and some wintergreen scented rubbing alcohol. You can find this alcohol in the first aid section of just about any store. It will be right next to the regular rubbing alcohol.
Put a mixture of half water and half wintergreen alcohol in the spray bottle. Clean the toilet (or litter box area or where ever) with this mixture. If there is a trash can or anything else near the toilet, clean under that too (and also under the litterbox if you are cleaning the cat area). For good measure, once the area is cleaned, I spray some more of the mixture on the area and let it air dry. This trick never fails!