Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Capture2text - Capture2Text enables users to quickly OCR a portion of the screen using a keyboard shortcut.
Shutter - Shutter is a feature-rich screenshot program.
TextSniper - Instantly extract any text from your Mac's screen
Snipping Tool - Use Snipping Tool to capture a screen shot, or snip, of any object on your screen, and then annotate, save, or share the image
dpScreenOCR - Program to recognize text on screen