Flickr - image and video hosting website
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
ImageShack - Unlimited space to host images, easy to use image uploader, albums, photo hosting, sharing, dynamic image resizing on web and mobile.
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.
Dropbox - Online Sync and File Sharing
500px - Connect, get inspired, and grow your skills.