Flickr - image and video hosting website
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
Shutter - Shutter is a feature-rich screenshot program.
Google Photos - All your photos are backed up safely, organized and labeled automatically, so you can find them fast, and share them how you like.
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