Write you names and wedding date on a wood heart and frame it. Have your guests sign smaller hearts and drop them via a small slot on the top. What a cute and unique guest book idea that you can display after your wedding.
I have also seen similar centerpieces that use epsom salts instead of sugar. You could also sprinkle a mix of pearls/gems. Sand (or sugar), faux pearls, a 3 candle. An easy DIY wedding centerpiece idea.