Perhaps, you want to have different family members or even pets add a few words/sounds to the greeting.  You may want to add a bit of your favorite holiday song to the beginning or end of the message.  

You can use Acoustica Mixcraft to record your message from the microphone.  Then drag in sound effects and music.  You should keep the message length less than 15 seconds. 

The music will have to be shortened which you can do by right clicking on the right hand side of the sound and resizing to the left.  Add a couple of volume points so that it fades out properly.  

Put your phone up to the speaker of your computer and record your message to your message machine. 

If this sounds fun, try Mixcraft or purchase Mixcraft to get started.