GIMP - GIMP is a multiplatform photo manipulation tool.
Imgur - Imgur is a free and simple image hosting service with image editing feature. Signup is optional.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Flickr - image and video hosting website
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.
Photobucket - Photobucket offers image hosting and free photo and video sharing.