alternative Guestbook ideas

On to the next decision: Whatever to do about the "guest book?" Both Austin and I don't know how we would use a book full of people's signatures, so we are talking about doing something different instead of a plain old book with blank pages and ivory satin cover.

Surprised?
(Everything else about our wedding is slightly off-traditional, so why wouldn't this be also!?)

Here are some ideas that I found through a few Google searches:

What about a poster?


Or a nice customized book?


Or how about notes put into a cool jar, that we figure out what to do with later?


Or my current favorite...a fingerprint tree!!