Perhaps purchase a polaroid camera and try this idea (instead of a photobooth or as a wedding favor). DIY Wedding Table Decoration Ideas - Novel Guest Book - Click Pic for 46 Easy DIY Wedding Decorations
10 of the best unusual wedding guestbook ideas - Flip out
For the modern, tech-savvy couple! An electronic guest book, such as an ipad or compact video recorder, is a fun way for guests to interact and a great alternative if you don't have a videographer but still want to capture video mementos.