I was first turned on to "vanity barcodes™" from my friend when I was in college. Although the one I saw was not from Vanity Barcodes™, it followed the same principal: as long as the barcode can still be scanned, you can create a very stunning design for something often forgotten. The first vanity barcodes™ I ever saw were from Vincent Chow's blog. I thought the umbrella barcode (pictured above) was quite extraordinary and subtle. However, Vanity Barcodes has—so to speak—raised the bar. View their creations on their website and hit the jump to see some that I think are quite spectacular.
Images via vincentchow.net and Vanity Barcodes