Scanbot - Scanbot is a mobile app that allows you to use your device's camera as a document scanner. The app is capable of scanning a large number of source materials, and it can handle QR codes as well.
NAPS2 - NAPS2 is a document scanning application with a focus on simplicity and ease of use.
Scanner Pro - Scanner Pro turns your iPhone into portable scanner in your pocket.
Simple Scan - Project information. Part of: The Gnome Project. Maintainer: Simple Scan Development Team. Driver: Simple Scan Development Team. Licence: GNU GPL v3.
Genius Scan - On The Go.
XSane - A good proposal for SANE-2 has been written.