I was at the 2008 Web2.0 Expo last week in San Francisco and stopped by the Instructables.com booth where they had a Laser Engraving Machine setup and were doing engravings for FREE for conference attendees. You could get either your laptop, iPod or iPhone (or any other device for that matter) engraved, as long as your provided them with vector art or high enough resolution bitmap art.

I provided them with a PNG file of a QR Code I generated (via Kaywa QR-Code Generator) with my entire email signature file, postal address, with links to my blog and twitter pages as well. It was a very large QR Code to say the least, in real world use it would not work on many handsets as it is too complicated. But, as a digital graffiti piece on my iPhone it was just fine.

Note: This article and QR engraving was mentioned recently on the Kaywa Blog as well… and I have since met a guy on Flickr who also engraved some QR codes on his iPhone as well!