It is a given.
Christmas usually involves a Christmas tree.
Let's try this...
There are some great ways to incorporate your tree as your Christmas party theme.
Some folks gather up all the decorations and a tree, then they get all their friends together and have a tree decorating party, along with lots of festive Christmas party food.
Another proven idea is to have several small trees set up and let your friends have a decorating contest. They can create the decorations (make sure you provide plenty of supplies) and have it completed within a certain time frame.
Along that same idea, one of my friends participates in a tree decorating contest each year for charity. Their organization decorates a tree and they cover it in dog and cat paw prints, pet toys, etc. (they are an animal support group). You could do the same for your favorite charities. Host a party where people bring assigned items for a theme tree for a charity and then have fun decorating the tree (or multiple trees and multiple charities if you have lots of friends coming).
Another idea to benefit charity and make use of your tree is to have everyone bring a gift to go under the tree for a Salvation Army Angel or other charity beneficiary that you and your friends would enjoy supporting.
A word of caution though...if going this route make sure everyone will be on board. You know your friends. With today's economy, not that anyone would want to deny a charity, but money may be tight for some of those on your guest list. If this is a possibility, be careful of what you ask your guests to bring.
One way to avoid this is to make bringing something optional (and maybe find a way to provide tax receipts to those who bring something too!).
How about making ornaments for a tree while at the party?
You could also divide into teams and go on a scavenger hunt to look for specific items for the tree.
A fun game to play at a Christmas tree party...remember the great Halloween game where you divide into teams, someone on each team is chosen to be a mummy, and the other players "wrap their mummy" in toilet player before the time is up? You can do this - just use green crepe paper and instead of making a mummy, make a Christmas tree. You can use sticky bows for decorations too. Lots of fun!