The following is a list of QR code readers for smartphones

iPhone

Bakodo (bako.do)
i-nigma Reader (itunes.apple.com/app/i-nigma-4-qr-datamatrix-barcode/id388923203?mt=8)
Barcode Reader (www.bardecode.com/en/news/199-shape-services-release-barcodereader-for-iphoneipod-touch.html)
Pic2Shop (www.pic2shop.com)
QR Code Reader and Scanner (itunes.apple.com/ca/app/qr-code-reader-and-scanner/id388175979?mt=8)
RedLaser (www.redlaser.com)

Android

i-nigma Reader (market.android.com/details?id=com.threegvision.products.inigma.Android)
Pic2Shop (market.android.com/details?id=com.visionsmarts.pic2shop)
RedLaser (market.android.com/details?id=com.ebay.redlaser)
Barcode Scanner (www.androidzoom.com/android_applications/shopping/barcode-scanner_clh.html)

Windows Phone

Pic2Shop (www.pic2shop.com)
i-nigma Reader (www.freewarepocketpc.net/ppc-download-i-nigma-barcode-reader-v1-4.html)
Quickmark (www.freewarepocketpc.net/ppc-download-quickmark-v3-3-barcode-reader.html)

Blackberry

ScanLife Barcode Reader (appworld.blackberry.com/webstore/content/1102)
Mobiletag 2D barcodes scanner (appworld.blackberry.com/webstore/content/6046)
Sccope US (appworld.blackberry.com/webstore/content/12464)