Not to long ago, Adobe released a free app for the iPhone called Photoshop.com Mobile. It's obviously and image editor, but it's usefulness comes from tying directly into your Photoshop.com account. The app is limited to some basic editing features, but I must say, it's quite nice for a first try.
You can choose a photo or take a photo to start editing.
The app has some simple, but nice features including color effects, crop, rotate, image effects, sketch and more. When your done, you can save or upload directly to your free Photoshop.com account for easy retrieval from any internet connected computer. Furthermore, users can connect to their Photoshop.com account and have access to their entire Photoshop.com library directly from the iPhone.