My FI and I are LARPers/Renactors, as are almost all of our friends. Our good friend made us these wooden round shields, and I painted them to serve as our guest books. We will have them displayed with sharpies, for everyone to sign, and then they will be hung on the wall in our home.

Honestly they are are probably the thing I am most excited about. The green one is FI's (he asked for the owl) and the orange one is mine. I just wanted to share because they make me really happy. Also they were a lot of work and I am pretty proud of how they turned out.
Re: Our DIY Guestbook Alternative
I love guest books that double as décor. Excellent!
Live Action Role Playing game. Never played one but they sound like a blast.