Please note: I'm not planning on getting married any time soon, but I'm thrilled to be able to share this idea/technique with folks who are!
Folks who gravitate towards older media (I am one of these folks) will always have a special place in their heart for things like film cameras and albums on vinyl. Using reloadable film canisters to send out "save the date" notices to your friends and family is not only an perfect way to show your love for whomever you're getting hitched to, but also for film.
These require some items you may not have around the house and take some time to design and put together, but in then end they're really worth it. The same technique could be used for a number of applications (moving or birth announcements, holiday greetings, or invites to any sort of super awesome gathering - even for the big day itself).
If you have any questions, need any advice/assistance, or would rather someone whip these puppies up for you feel free to comment, or shoot me a note here or on Twitter.