We're not doing OOT bags, since I'm pretty sure we won't know any final numbers of guests until we count them on the plane!
When we get back from the wedding, the FI and I want to frame individual pictures of each guest and us in a hollow frame that we can fill with sand and shells from the beach we were on.
We need to do a bit of preplanning here, to make sure that we get a picture with each and every guest on our wedding day, and we'll print out the picture, frame it, then mail it to the guests with the thank you cards after the wedding.
The only snag I've come accross is where to find these frames that I can fill with sand!