Adobe Photoshop Mix is a free cloud-based photo enhancement app for the iPad. It's oriented very much as the image editing novice, but still has a few surprising extras for you to try.
These start at the very beginning, as Mix doesn't just open regular JPEGs: you can also open Photoshop PSDs, or even load and work with a single PSD layer.
As with other tools, you're able to manually tweak contrast, colours, exposure and more, fix common problems (angled images, shaky camera work) or apply predefined "looks" to instantly enhance your images.
Smart selection tools help you to select an area or object with a finger. You can then apply effects to that area alone, extract the object, or place it in another photo for a quick composite. Adobe's excellent content-aware fill technology means the results are generally great.
Photoshop Mix processes some of its more advanced functions in the cloud, and so won't overly tax your iPad's CPU. But of course this also means you'll need a good network connection, especially if you're working with large images.
When you're finished, the photo may be emailed, printed, uploaded to Facebook, and more.
Forget the usual feeble photo "enhancement" apps - Photoshop Mix's selection tools, smart enhancements, content-aware fill and other features mean it really stands out from the crowd. Go grab a copy immediately.