Aviary Phoenix - Advanced Image Editor

Phoenix is a full-featured image editor with layers, masks, effects, undo history, and all that other good stuff found in desktop image editors. All the tools you need to edit your images.

Website: Phoenix by Aviary - Advanced online image editor - http://www.aviary.com/tools/image-editor 
Price: Free
Desktop Alternative Software: Photoshop - Windows Paint - Paint.net - Gimp - Paint Shop..