There is also a trick of simmering some drops of vanilla in a small amount of water on the stove top along with a few sticks of cinnamon.
What I have found to work best is simmering a pot of water with 'Christmas' potpourri. This fills the house quickly with the wonderful smell of pine and cinnamon (mostly cinnamon with a pinch of ginger). It is a quick way to fill your house before guests arrive with the Christmas spirit or just to have your house begin to feel a lot like Christmas.
I've had a small pot on my stove for the past 3 days and just turn it on whenever we want that smell in the house. We also have a live Christmas tree up in the house that smells wonderfully pine'y' but the potpourri adds that extra cinnamon in the air.