SwivelCard is an astonishingly smartly designed business card that also includes a USB stick interface -- when folded in a particular way, the business card transforms into a USB stick that can be stuck in a USB port and link the user to a particular website.
You can even customize which website you want to associate with individual SwivelCards. For example, if you're a freelance journalist, you can personalize the web content you want to show to particular contacts you might meet.
Seeing as how it has a digital interface, the SwivelCard also includes the ability to track usage. You can easily see where your business cards have ended up, and how many people are accessing them.
But how do you get a USB interface on a paper business card? The developers of SwivelCard used a special metallic ink to print USB contact strips and embed a small chip in the paper.