We have a tradition in our family of giving our kids an ornament every year. They also get one from their grandparents. We try to select something that will have special meaning and/or is related to something which happened during the year. We have given a bus ornament for a child starting kindergarten, 1st Christmas to a new baby, Flute to our new flute player (who quit a few months after Christmas- now its a great story teller), new driver, braces, etc. There are a lot of places to get ornaments that have to do with events, places, etc.
We continue to give them to the kids until their 18th year. At that time, they are on their own to create their own memories- and may very well be out on their own. When they do leave the nest, they take their box of ornaments with them to decorate their own tree with lots of memories!