Now that Google has placed its virtual blessing on two dimensional QR (Quick Response) barcodes, you'll need to create them for use on your brick and mortar store or in your print marketing materials if you really, really want to be in their good graces.
Here are a few resources that we here at Website Magazine have used in the past (in our print magazine) or have come across during our routine travels on the 'Net that we're immensely impressed with.
ScanLife: In each and every edition of Website Magazine, you'll see two-dimensional QR barcodes on a few of our editorial and advertising pages. There are a few reasons that we use ScanLife over their open source competitors - namely that it covers the broadest number of mobile phones/smartphones and that some very valuable analytics come with it. If you have anything to do with advertising you know how important that is to the bottom line. Creating barcodes (for non-commercial purposes) is free and the rates are reasonable for commercial enterprises.
Kaywa.com: One of the more popular QR code generators on the market and a mainstay for many users (and believer in these codes). Users have the choice between multiple content types include URL, Text, Phone number of SMS. I personally use Kaywa routinely, even using the generated barcodes as my Facebook profile picture (yes, I do get some strange comments but my fellow geeks seem to love it).
ZXing (Zebra Crossing): If I didn't know any better, I would say that ZXing is going to be the de facto standard for QR Code readers and generators. Originally, ZXing was limited to decoding software but this Google hosted application has made major strides in the past year and it's generator is one of the absolute best. Users can choose from a number of content types (URL, SMS, Calendar, Event, Message, etc) and download or embed the rendered QR code.
I believe those listed above to be the best quick response code generators available. Others however include QRStuff.com, Mobile-Barcodes.com, INVX.com and Heroku.com.