I just came across this sweet wedding favor concept from the Martha Stewart Weddings site. Give your guests tulip bulbs to plant at home and make them inviting by using these paper templates before they bud and bloom. I love the idea of making little faces or hands or characters for a more intimate gathering. There are also endless possibilities for the containers. I once did something similar to this when I gave a friend a sprouted Amaryllis plant that had not bloomed yet, I used a living flower instead of paper though (which definitely has a shorter shelf life). The best part is you can pick shades from your wedding colors, enhancing the overall look of the event and giving everyone a bright, living piece to take away. See how here.
P.S. This would be fun for dinner parties, birthdays, and other events, too.