A Book on a Hook - Usable Conference Badge

I've had people give me their business cards at conferences, and the cards just sit in the bottom of my bag. If I scanned someone's badge and immediately added them to my contact list that'd certainly lower the barrier to getting in touch with them later.

That having been said, I opted out of this as Google did not let you choose what contact info to have encoded on the badge. You had the choice of encoding all of the info you gave in your registration (which in my case, included my home address!) or nothing but your name. So if you're going to go this route, make sure you give people control over what they're willing to share.