XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
Wondershare PDFelement - All-in-one PDF editor
IrfanView - IrfanView ... one of the most popular viewers worldwide.
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.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
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.