Pixoh is an innovative web-based application for image editing. You can upload an image or point to a URL, or just use their bookmarklet to open any image while browsing the web. It then opens a new web-page with some embedded tools for simple image editing. No plugins required. Right now, the functionality is somewhat limited: resize, crop, rotate, and basic adjustment of things like brightness and contrast. Images can then be saved to Flickr, or downloaded in any of 5 common image formats. It's no Photoshop (yet), but for quick edits it is a great tool!