Blot up as much moisture as possible. Rub the spot with a solution of vinegar or lemon juice and warm sudsy water. Blot a few times, then pour straight club soda over the spot and blot again. Place a dry towel over the stain and put a heavy object (like a book) on top of it. Replace towel if it becomes soggy, and repeat blotting.

For cat accidents:

Follow the same steps but, when the spot is dry, rub with a cloth dampened in ammonia. This will take the offensive odor away and it will prevent the cat from ever going in that spot again.