Looking for an innovative invitation idea (or having a desert-island themed wedding?), then Message in a Bottle by Urbanity could be just what you’re looking for. (Plus they have the cachet of having been featured in Oprah’s O magazine. Or perhaps that only matters to Oprah-obsessive me.)
Write your message, roll up and tie the scroll, attach the addressed label to the bottle, push in the cork and drop the bottle in the postbox. No extra packaging required. They cost $23.95 for six.