Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Wondershare PDFelement - All-in-one PDF editor
Capture2text - Capture2Text enables users to quickly OCR a portion of the screen using a keyboard shortcut.
Foxit PhantomPDF - Edit PDF files with our feature-rich PDF Editor. Download Foxit PDF Editor to convert, sign, scan / OCR & more. A speedy PDF Editor alternative to Adobe Acrobat.
ksnip - Ksnip is a Qt based cross-platform screenshot tool that provides many annotation features for your screenshots. - DamirPorobic/ksnip
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.