TextSniper - Instantly extract any text from your Mac's screen
GImageReader - gImageReader is a simple Gtk/Qt front-end to the Tesseract OCR Engine.
LensOCR - Scan anything from your Mac's screen.
Adobe Scan - Scan anything into a PDF using your mobile device.
Easy Screen OCR - Easy Screen OCR helps users capture screenshot and grab text from images.
Tesseract - Tesseract is an optical character recognition engine for various operating systems