Photoshop Express seems easy to use. You can crop, adjust hue and saturation levels as well as applying other airbrushing techniques. Unfortunately you can't use layers or add text. But at least it should mean the end of really crap photos on Facebook.
All changes can be undone and you are always given the option to revert back to the original image. Photoshop Express runs on any web browser on Windows, OS X or Linux because it's a Flash 9 application.
Another cool feature is the Flickr style 2GB of free storage space which can be linked to Facebook and MySpace. Adobe says that Photoshop Express will be synced with Flickr in the next few weeks. Happy days.