I love this idea. An envelope guest book. You just take a store-bought scrapbook/album and glue envelopes into it. Lay out colored pieces of paper for guests to jot notes down on, and then they can place them in the envelopes.
Heart Paper Chains: Cut construction paper into strips, fold each strip in across its width, bend the loose ends in without folding them, bring them together and staple. Repeat with the next strips, making a heart paper chain.