Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
Flickr - image and video hosting website
imgbox - Imgbox is a free image hosting service.
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.
PostImage.org - Provides free image upload and hosting integration for forums.
500px - Connect, get inspired, and grow your skills.