While it won’t quite match up to those (somewhat insane) people who want the full powers of the Mac version of Photoshop in an iPhone application, Photoshop.com Mobile does let you edit photos stored on your iPhone, adjusting qualities such as exposure, saturation, and tint as well as cropping, rotating, and flipping. In addition you can apply effects, such as pop art, vignette, sepia, and black & white. There are even multiple levels of undo/redo if you make a mistake.
When you’re done tweaking your photo to its desired state, you can upload your new picture to your Photoshop.com account. You can also view other pictures you’ve saved from your iPhone or computer.
Photoshop.com Mobile for iPhone is a free download and requires iPhone OS 2.0 or later. Photoshop.com offers free accounts with 2GB for free, but an account isn’t required to use the iPhone app.