We have at least one tree in every room of our home each year, and most of them are some kind of theme. Sometimes it's a loose theme, maybe based on the room, but a theme, none the less.
In Jacob's room, we do a Coca-Cola theme. It's very simple, but that's all he'll allow me to do in there. He is 16, you know. He has a tiny little tabletop tree, about 3' high. It sits in a burlap bag, tied with a red velvet bow. It has a string of white lights on it..and empty Coke cans, tied on with red curling ribbon. Very simple, but really cute.
This tree was in our bathroom. It is decorated in all gold and pearls. The lights are even little pearls. I just use one string of lights on it, so that it's just a soft glow. The ribbon is from the craft section and the pearls are from our wedding reception. I used them on the tables along with oil lamps on each table.
This is my jingle bell tree. All of the decorations on it are jingle bells. The ribbon looped on it has the words to the song...you guessed it..."Jingle Bells" written on it.