Capture2text - Capture2Text enables users to quickly OCR a portion of the screen using a keyboard shortcut.
Everything by Voidtools - Everything. Locate files and folders by name instantly. Everything. Small installation file. Clean and simple user interface.
TextSniper - Instantly extract any text from your Mac's screen
DocFetcher - DocFetcher is a portable German/English open source desktop search application.
dpScreenOCR - Program to recognize text on screen
Recoll - Recoll is a desktop full-text search tool. Recoll finds keywords inside documents as well as file names.