Another business card idea is to put a demo on a USB key and make the USB key your business card, or glue it to one. If you are willing to spend a bit more, you can get wafer-thin usb drives, and/or higher capacity ones, and make a bootable Linux distro on it, so it can be plugged into a PC and your fantabulous demo pops up. Also see

http://gizmodo.com/gadgets/peripherals/usb-flash-card-is-waferthin-holds-a-gig-203617.php