Apparently my favorite ideas just keep coming from pinterest. This one isn't exactly for the wedding but it's a gift that can be given to the bride and groom on their first Christmas together. Or a bride can make one herself to cherish the memory.
Basically what you do is cut the invite into strips, then curl it around something (if it's hard enough paper it should stick like that) then put it inside a clear ornament. Clear ornaments should be easy to find around Christmas time (maybe stock up after Christmas if you know a wedding is coming up). This picture even adds on a little charm and you can always customize it by writing the date on it or their names. I love this idea. Too bad I missed my best friend's first Christmas with her hubby.