Interactive contact sharing isn’t new stuff around. Most of them use RFID tags or other wireless toys to share info between them. Other simple way is to store tour contact info in USB flash disk that starts up when plugged in. Or there is an old-fashioned way – use paper contact cart which probably is most reliable but less cool.
Here it is another great solution that can be easily made at home – an USB business card which actually looks like real card but with USB connector and a small Attiny85 chip on it. This card acts as a keyboard which types text on any word processing program once caps lock key is pressed few times. Design is very minimal – even USB connector is made on PCB itself. Microcontroller runs USB by using well known V-USB solution.