Well, until today, when I noticed googles Print Ads 2D Barcodes technology. The idea is to put a small 2D barcode next to the printed ad, in which a URL to a website is encoded. You can then take a snapshot of the barcode with your mobile phone, have software on the phone automatically decode the 2D barcode into the URL, and lastly open a web browser, again on the phone, taking you to the URL.
That is kind of cool, I think :-)
Of course, google has software to decode 2D barcodes, which runs on J2ME and of course Android.
But there are others too. Take a look at Nokia mobile codes, where you can create 2D codes and get scanner software for your phone. To the right is a 2D barcode of the URL to this blog. Sadly, I did not find any barcode scanner software ready for download to my Sony Ericsson W810i. Guess I will have to build zxing and run is on J2ME then.