Photoshop Touch for iOS packs a number of the core Photoshop features, optimised for use on tablets. In particular, it handles layers, features pro-style effects, and allows users to touch up photos. One nice little feature is the Scribble Selection Tool: a lazy squiggle over the area of your choice simplifies the way in which you select areas. Elsewhere, it also features some baked-in Facebook and Google Image Search features.
It is expected to be complemented by further iOS Adobe Touch Apps in the near future. In the meantime, it costs £6.99 and can be purchased from the App Store. [iTunes]