Chalkboards are extremely trendy right now! To give your guests something sweet to read, display a relationship timeline chalkboard. If you want to make your own chalkboard, you can purchase chalkboard paint at a majority of craft stores.
Assign each table a different anniversary year (i. table 1 would be anniversary year etc.) and let the guests at that table write notes to be opened on that particular anniversary year (a unique alternative to a wedding guest book).