If I have to pull out my mobile device to read QR codes, I want an app that's fast, locks on, and scans codes quickly without any fuss. While there's a plethora of QR code scanners on the App Store, one in particular I've fallen in love with is Scan. Maybe it's because Barcode Scanner on the Android Marketplace is so damn slow (I'm tired of how long it takes the camera to focus), and I was blown away by how fast Scan was... on an iPod touch (which comparatively has a pretty crappy camera). As soon as I opened the app, I simply placed the QR code inside of the sights and just as instantly it opened a web page in its own browser. If it can't scan a QR code (which is rare), Scan won't complain. Just relocate your device or find a higher quality image: how painless Scan is to use is fantastic. Plus, it saves a history of everything you scanned in a simple list that's perfect for how often I use it. Sure there are other apps that let you generate QR codes or offer a lot more features, but for sheer simplicity and fast scanning, Scan has become the mainstay reader on my device. You can download it for free on the App Store.