I've been to a 50th anniversary party where a quilter laid out precut (STARCHED etc) squares and the pens to write on them. She invited everyone to at least sign a square or write a small note.
She went home and turned the signatures squares into a quilt (I think she used a small log cabin around each square).
It was a beautiful quilt when she was done and so personalized for the couple.
If you like this idea but there is no party, I bet you could send out the quilt squares to their friends and family with simple instructions and a return envelope?