Favor Fun, part deux
On to the usable category...
Let it be an item that your guests will actually use. Think about your family and friends, what are their rituals and how do they like to have fun?
If your family enjoys wine, maybe a wine stopper. Firefighters and policemen abundant on your guest list? Maybe some koozies would be a good idea. Music lovers at your shin dig? A custom CD. Be creative, and then the packaging can match the scheme of your wedding.