QR codes are all the rage in marketing these days. The two-dimensional bar codes store tons of marketing information, can be printed on nearly any kind of surface (think cake frosting and temporary tattoos), and, best of all, the tools needed to create and read them are free.
This article from SearchEngineWatch.com lists 14 tools, tactics, and best practices marketers should know about QR codes to get started. The article has plenty of basic information about QR codes, along with links to the free code generators and readers.
Along with the helpful tools and information, the author provides a QR codes checklist and worksheet to help plan a QR marketing campaign.