Guests sign wine corks instead of a guest book. After the wedding you can put them on display in a vase, bowl, or even create a fun cork board with the signatures facing out. Or guests sign wine bottles to be opened on anniversaries
Have a need for speed? Ask guests to sign your motorcycle helmets, like this couple did. With motorcycle enthusiasts in my own family, this guest book alternative would surely be everyone's top pick, if they could choose.