I already posted about campaigns that use barcodes, camera phones and traditional media to create a "transmedia" campaigns, and AdRants brings the topic back into the limelight with its post on Northwest Airlines' campaign in Japan using QR codes by
[Update: April 2, 2006] QR Codes are a product of Denso Wave. Semacode Tags are by Semacode.
PaperClick, FCB Tie Barcodes and Cellphones
SoundAds: Print and Sound
Feedback to Print Ads Through Camera Phones
Digital Billboards: Overview