Free Online Image and Photo Editors
The Web 2.0, in my opinion will soon be called Web 3.0 as more software companies take advantage of RIA (Rich Internet Application) and HTML5 to push the boundaries of the status quo and provide true applications that equal their desktop or standalone counterparts in functionality and usability. A case in point is Splashup (http://www.splashup.com/splashup/) and Pixenate (http://pixenate.com/); a photo editor and an image editor that provide the same functionality as many counterparts on the desktop.
Splashup is a full feature image editor tool. Written in Adobe flash, It is accessible from anywhere and integrates with most top photo web sites and offers Adobe Photoshop or CS5 features like layers, multi picture editing and pixel level control. They offer a sleek UI with all the standard controls you would find in software like MS-Paint (Windows) or Paintbrush (Mac).
They also have a lite version, which can be installed on a PC, MAC or mobile device like iPAD.
The other tool I have found that is great for create or modifying icons is the Pixenate web application. This software is for photos and offers many fantastic tools to add interesting effects to an existing photo like: cropping and resizing, vertical or horizontal flipping, rotation, normalizing effects for noise reduction, photo re-alignment and brightening. You can also spruce the photos color, remove red eye and whiten teeth.
The API is accessible here: http://pixenate.com/pixenate/docs/API-Reference.html. They also have a complete documentation on using Pixenate and also for developers which is available at this address: http://pixenate.com/productinfo/Documentation.html
Do you need to install Pixenate in your own application as part of a greater software system. Installation instructions are accessible from this address: http://pixenate.com/pixenate/docs/Installation-Guide.html and as well a faily complete customization guide: http://pixenate.com/pixenate/docs/Customization-Guide.html
I find both these tools so useful when I need to adapt an image for an application or article as I am often writing from different locations I need tools where I can access my work wherever I am keep everything in sync.