I see a lot of conference badges.
WebEvents Global specializes in print on demand badges that make the conference check-in experience a breeze.
I just finished reading a blot post about
Book on a Hook, a badge from
The Web and Beyond 2010 event, held in Amsterdam.
They showcase badge being a useful as book that the attendee can actually get value out of, beyond just identification.
Google I/O created a very informative and entertaining booklet for their 2009 event.
I'm not 100% sold on the usefulness of your badge being a book, but I can how for some events it might work well.
I've brainstormed with various people on what makes the perfect event badge, from a high tech RFID card to giving every attendee an IPod Touch for use as a badge.
I would like to hear other innovative ideas for badges from attendees and event managers.