Hang a picture frame with glass in it and give your guests dry erase markers for a fun photo! (Ok the frame idea is cute but not why I'm pinning this- ISN'T THE BRIDE AND GROOM OUTFITS ADORABLE!!!??? You should get similar styles! You both would rock them!
144 Personalized 1.5oz Wedding Favor Glass Shot by Factory21, $161.24 (Cute idea--not sure how much you're looking to spend on favors but this seller has a lot of options on Etsy for personalized shot glasses)