QRCODE's are ubiquitous today. Realtors, companies, and other commercial entities use them to allow customers to visit their website without typing anything. All you do is aim your smartphone at the QRCODE and voila! it takes you to the designated web site.
If the website is your own personalized we content, you can show off your photo, bio, profile, hobby's, online chat session, links to other websites, your location, etc. The web site can use geo-location services to pinpoint you and the visitor or a syatem of QRCODE signs can be placed in a conference hall to designate location when there is no Wi-Fi or 3g/4g signal.
Also QRCODES can provide text messages too when there is no Internet signals. In that case you would need two QRCODES, one for Internet or non-Internet presence. The QRCODES could be moderately large so people could aim at them from far away so as not to be obvious about it. Or one could be worn on your back or the back of your baseball cap.