Tesseract - Tesseract is an optical character recognition engine for various operating systems
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.
Onlineocr.net - Free Online OCR service allows you to convert PDF document to MS Word file, scanned images to editable text formats and extract text from JPEG/TIFF/BMP files
Scanner Pro - Scanner Pro turns your iPhone into portable scanner in your pocket.
Prizmo - Prizmo is a scanning application for Mac with Optical Character Recognition (OCR) in over 40 languages with powerful editing capability, text-to-speech, and iCloud support.
Genius Scan - On The Go.