Here's an idea for a wedding reception decoration/wedding stuff. Get a note from wedding guests by providing a small notepad where they can write short messages for you, and station a jar beside it so they can drop their note in it.
I had a wedding wishing well during my wedding and I have since put all the notes in a scrapbook. Here's a wedding jar from my ninong's wedding -
And the bride and groom can also leave inspirational messages for guests. Make sure though that the jar is big enough to put your hand in.