Several design apps for tablets are Sketchbook Pro, Fresco Paint Pro and Paperless. Other design apps include Sketcher Lite and Skitch.
Sketchbook Pro provides a range of professional sketching and painting tools ranging from 60 preset brushes, layer blending and customizable brush settings. Fresco Paint Pro has a variety of brushes, filters and effects. It saves the work every few minutes and the files can be exported to Photoshop PSD format.
Paperless allows drawings to be created with watercolors, feather, pencil and brushes. The thickness, size, opacity and smoothing settings can be altered with a customizable engine. The files can be saved as PNGs.