Layers is one of the most useful app for the iPad, especially for a painter or an aspiring artist. The app allows you to work on multiple layers which makes it easy to edit; create the artwork and to add or delete and even rearrange the layers. The app is very neat and convenient to use.
The app features a history pallet that can be used do undo/redo commands upto 30 levels. You can even e-mail your work or add to its online gallery. The app costs 4.99 dollars. [link]